| Term | Definition |
|---|---|
| adhesion | The attractive force between water molecules and other polar substances, allowing water to stick to different surfaces. |
| cohesion | The attractive force between water molecules that causes them to stick together, resulting from hydrogen bonding. |
| evaporative cooling | The process by which the evaporation of water removes heat from an organism or environment. |
| heat of vaporization | The energy required to convert a liquid to a gas, enabling water to remove heat from organisms through evaporative cooling. |
| homeostasis | The maintenance of stable internal environmental conditions in an organism despite external and internal changes. |
| hydrogen bond | Weak attractive forces between a hydrogen atom bonded to an electronegative atom and another electronegative atom, occurring between or within biological molecules. |
| polar covalent bonds | Chemical bonds between atoms where electrons are unequally shared, resulting in partial positive and negative charges. |
| polarity | The unequal distribution of electrical charge in a molecule, resulting in one end being partially positive and the other partially negative. |
| specific heat capacity | The amount of energy required to raise the temperature of a substance by one degree, allowing water to resist rapid temperature changes. |
| surface tension | The property of water that allows its surface to resist breaking, resulting from hydrogen bonding between adjacent water molecules. |
| Term | Definition |
|---|---|
| carbohydrates | Biological molecules composed of carbon, hydrogen, and oxygen that serve as a primary source of energy and structural support in living organisms. |
| carbon | An element that is the most prevalent component of biological molecules and forms the backbone of all organic compounds. |
| hydrogen | An element that is a prevalent component of biological molecules and is bonded to carbon, oxygen, and nitrogen in macromolecules. |
| lipid | Hydrophobic or amphipathic biological molecules composed primarily of carbon, hydrogen, and oxygen that store energy and form cell membranes. |
| macromolecules | Large, complex molecules composed of many atoms that are essential for life processes, including carbohydrates, proteins, lipids, and nucleic acids. |
| nitrogen | An element used in the building of nucleic acids and proteins as part of amino groups and nitrogenous bases. |
| nucleic acid | Macromolecules composed of nucleotides containing carbon, hydrogen, oxygen, nitrogen, and phosphorus that store and transmit genetic information. |
| oxygen | An element that is a prevalent component of biological molecules and is found in carbohydrates, lipids, proteins, and nucleic acids. |
| phospholipid | Amphipathic molecules with hydrophilic phosphate heads and hydrophobic fatty acid tails that form the basic structure of the cell membrane. |
| phosphorus | An element used in the building of phospholipids and nucleic acids, particularly in phosphate groups. |
| protein | Macromolecules composed of amino acids linked together, containing carbon, hydrogen, oxygen, nitrogen, and often sulfur, that perform diverse functions in cells. |
| sulfur | An element used in the building of proteins, often found in disulfide bonds between amino acids. |
| Term | Definition |
|---|---|
| covalent bond | Chemical bonds formed by the sharing of electrons between atoms, which can be broken or formed during macromolecule reactions. |
| dehydration synthesis | A chemical reaction that joins two smaller molecules together through covalent bonding by removing water, resulting in the formation of a larger molecule. |
| hydrolysis | A chemical reaction that breaks down molecules by cleaving covalent bonds through the addition of water, splitting polymers into smaller monomers. |
| monomer | Small individual molecules that serve as the building blocks for larger polymers. |
| polymer | A large molecule composed of many monomers linked together through covalent bonds. |
| polymerization | The process by which many monomers are connected together to form a polymer. |
| Term | Definition |
|---|---|
| cellulose | A polysaccharide polymer composed of glucose monomers that provides structural support in plant cell walls. |
| covalent bond | Chemical bonds formed by the sharing of electrons between atoms, which can be broken or formed during macromolecule reactions. |
| glycogen | A polysaccharide polymer that serves as an energy storage molecule in animals. |
| monomer | Small individual molecules that serve as the building blocks for larger polymers. |
| monosaccharides | Simple sugars that serve as monomers (building blocks) for polysaccharides and carbohydrates. |
| polymer | A large molecule composed of many monomers linked together through covalent bonds. |
| polysaccharides | Complex carbohydrates formed by linking many monosaccharide monomers together through covalent bonds. |
| starch | A polysaccharide polymer that serves as an energy storage molecule in plants. |
| Term | Definition |
|---|---|
| cholesterol | A steroid molecule found in the plasma membranes of vertebrate animals that regulates membrane fluidity and stability. |
| fats | Lipids composed of glycerol and fatty acids that provide energy storage, support cell function, and can provide insulation in mammals. |
| fatty acid | Organic compounds consisting of a carboxyl group attached to a long hydrocarbon chain; can be saturated or unsaturated. |
| hydrophobic | Water-repelling; referring to nonpolar molecules or regions that do not interact favorably with water. |
| lipid | Hydrophobic or amphipathic biological molecules composed primarily of carbon, hydrogen, and oxygen that store energy and form cell membranes. |
| lipid bilayer | A double layer of phospholipids that forms the basic structure of cell membranes and plasma membranes. |
| nonpolar | Referring to molecules or groups with even distribution of electrical charge, making them hydrophobic. |
| phospholipid | Amphipathic molecules with hydrophilic phosphate heads and hydrophobic fatty acid tails that form the basic structure of the cell membrane. |
| plasma membrane | The selectively permeable membrane that surrounds the cell, composed of phospholipids, proteins, and other molecules that regulate what enters and exits the cell. |
| saturated fatty acid | Fatty acids that contain only single bonds between carbon atoms. |
| steroid | Lipids with a four-ring carbon structure that function as hormones supporting growth, development, energy metabolism, and homeostasis. |
| unsaturated fatty acid | Fatty acids that contain at least one double bond between carbon atoms, causing the carbon chain to kink. |
| Term | Definition |
|---|---|
| 3' end | The end of a nucleic acid strand defined by the three prime hydroxyl group of the sugar. |
| 5' end | The end of a nucleic acid strand defined by the five prime phosphate group of the sugar. |
| adenine | A purine nitrogenous base found in both DNA and RNA that pairs with thymine in DNA or uracil in RNA. |
| antiparallel | The orientation of the two DNA strands running in opposite directions, with one strand oriented 5' to 3' and the other 3' to 5'. |
| base pairing | The specific pairing of nitrogenous bases between DNA strands (A-T and C-G) or in RNA (A-U). |
| covalent bond | Chemical bonds formed by the sharing of electrons between atoms, which can be broken or formed during macromolecule reactions. |
| cytosine | A pyrimidine nitrogenous base found in both DNA and RNA that pairs with guanine. |
| deoxyribose | A five-carbon sugar found in DNA nucleotides. |
| DNA | Deoxyribonucleic acid; a double-stranded nucleic acid that stores genetic information using deoxyribose sugar and thymine as a nitrogenous base. |
| double helix | The three-dimensional structure of DNA consisting of two antiparallel strands twisted around each other. |
| guanine | A purine nitrogenous base found in both DNA and RNA that pairs with cytosine. |
| hydrogen bond | Weak attractive forces between a hydrogen atom bonded to an electronegative atom and another electronegative atom, occurring between or within biological molecules. |
| nitrogenous base | A nitrogen-containing molecule that is part of a nucleotide; includes adenine, thymine, guanine, cytosine, and uracil. |
| nucleic acid | Macromolecules composed of nucleotides containing carbon, hydrogen, oxygen, nitrogen, and phosphorus that store and transmit genetic information. |
| nucleotide | The monomer unit of nucleic acids, consisting of a five-carbon sugar, a phosphate group, and a nitrogenous base. |
| phosphate | A chemical group that is part of the nucleotide structure and forms covalent bonds between nucleotides in a nucleic acid strand. |
| ribose | A five-carbon sugar found in RNA nucleotides. |
| RNA | Ribonucleic acid; typically a single-stranded nucleic acid that uses ribose sugar and uracil as a nitrogenous base. |
| thymine | A pyrimidine nitrogenous base found in DNA that pairs with adenine. |
| uracil | A pyrimidine nitrogenous base found in RNA that pairs with adenine. |
| Term | Definition |
|---|---|
| alpha-helix | A coiled secondary structure of a protein formed by hydrogen bonding between backbone atoms of the polypeptide chain. |
| amino acid | Organic molecules that serve as the building blocks of proteins, each composed of a central carbon atom bonded to a hydrogen atom, a carboxyl group, an amine group, and a variable R group. |
| beta-pleated sheet | An extended secondary structure of a protein formed by hydrogen bonding between backbone atoms of the polypeptide chain, creating a zigzag pattern. |
| disulfide bridge | Covalent bonds formed between sulfur atoms in cysteine R groups that stabilize tertiary protein structure. |
| hydrogen bond | Weak attractive forces between a hydrogen atom bonded to an electronegative atom and another electronegative atom, occurring between or within biological molecules. |
| hydrophobic interaction | Interactions between nonpolar R groups that cluster together in the interior of a protein to avoid contact with water, contributing to tertiary structure. |
| ionic interaction | Electrostatic attractions between oppositely charged R groups that stabilize tertiary protein structure. |
| peptide bond | Covalent bonds formed between the carboxyl group of one amino acid and the amine group of another amino acid, linking amino acids together in a protein chain. |
| polypeptide | A chain of amino acids linked together by peptide bonds. |
| primary structure | The linear sequence of amino acids in a polypeptide chain, determined by the specific order of amino acids in the protein. |
| quaternary structure | The arrangement and interactions of multiple polypeptide chains within a protein complex. |
| R group | The variable side chain of an amino acid that determines its chemical properties (hydrophobic/nonpolar, hydrophilic/polar, or ionic) and influences protein structure and function. |
| secondary structure | Local folding patterns in a protein formed by hydrogen bonding between atoms of the polypeptide backbone, including alpha-helices and beta-pleated sheets. |
| tertiary structure | The three-dimensional shape of a protein resulting from interactions such as hydrogen bonds, hydrophobic interactions, ionic interactions, and disulfide bridges between R groups. |
| Term | Definition |
|---|---|
| chloroplasts | Specialized organelles found in plants and photosynthetic algae that contain a double membrane and serve as the location for photosynthesis. |
| compartmentalization | The division of the eukaryotic cell into distinct membrane-bound regions that separate different metabolic processes and enzymatic reactions. |
| endosymbiosis | The process by which free-living prokaryotic cells were engulfed by larger cells and became membrane-bound organelles. |
| eukaryotic cell | Cells that contain a membrane-bound nucleus and internal membrane-bound organelles, found in animals, plants, fungi, and protists. |
| internal membrane | Membranes within eukaryotic cells that divide the cell into compartments with specialized functions. |
| membrane-bound organelle | Specialized structures within eukaryotic cells enclosed by a membrane that perform specific cellular functions. |
| mitochondria | Membrane-bound organelles in eukaryotic cells that are the primary site of aerobic cellular respiration and ATP synthesis. |
| prokaryotic cell | Cells that lack a membrane-bound nucleus and internal membrane-bound organelles, typically bacteria and archaea. |
| Term | Definition |
|---|---|
| adenosine triphosphate | The primary energy currency of cells that powers cellular functions. |
| aerobic cellular respiration | The metabolic pathway that uses oxygen as the terminal electron acceptor to generate ATP from biological macromolecules. |
| chemical modification | Changes made to proteins in the Golgi that affect their function or cellular location. |
| chloroplasts | Specialized organelles found in plants and photosynthetic algae that contain a double membrane and serve as the location for photosynthesis. |
| double membrane | Two layers of membrane found in mitochondria and chloroplasts that create separate compartments for different cellular processes. |
| endomembrane system | A group of membrane-bound organelles and subcellular components that work together to modify, package, and transport polysaccharides, lipids, and proteins within cells. |
| endoplasmic reticulum (ER) | A membrane-bound organelle that provides mechanical support, maintains cell shape, and plays a role in intracellular transport. |
| glycosylation | A chemical modification of proteins that takes place within the Golgi and determines protein function or targeting. |
| Golgi complex | A membrane-bound organelle consisting of flattened membrane sacs that folds and chemically modifies newly synthesized proteins and packages them for trafficking. |
| hydrolytic enzyme | Enzymes found in lysosomes that break down and digest cellular materials. |
| intracellular transport | The movement of materials within a cell, facilitated by organelles like the endoplasmic reticulum. |
| lipid | Hydrophobic or amphipathic biological molecules composed primarily of carbon, hydrogen, and oxygen that store energy and form cell membranes. |
| lipid synthesis | The production of lipids, a function carried out by smooth endoplasmic reticulum. |
| lysosomes | Membrane-enclosed sacs that contain hydrolytic enzymes for digesting material and play a role in programmed cell death. |
| mitochondria | Membrane-bound organelles in eukaryotic cells that are the primary site of aerobic cellular respiration and ATP synthesis. |
| nuclear envelope | A membrane-bound component of the endomembrane system that surrounds the nucleus. |
| organelle | Membrane-bound or non-membrane-bound structures within eukaryotic cells that perform specific cellular functions. |
| photosynthesis | The series of reactions that use carbon dioxide, water, and light energy to produce carbohydrates and oxygen, allowing organisms to capture and store energy from the sun. |
| plasma membrane | The selectively permeable membrane that surrounds the cell, composed of phospholipids, proteins, and other molecules that regulate what enters and exits the cell. |
| polysaccharides | Complex carbohydrates formed by linking many monosaccharide monomers together through covalent bonds. |
| programmed cell death | Programmed cell death, a controlled process in which a cell actively participates in its own destruction. |
| protein | Macromolecules composed of amino acids linked together, containing carbon, hydrogen, oxygen, nitrogen, and often sulfur, that perform diverse functions in cells. |
| protein synthesis | The process by which ribosomes build proteins according to mRNA sequences. |
| ribosomes | Non-membrane subcellular structures composed of ribosomal RNA and protein that synthesize proteins according to messenger RNA sequences. |
| rough endoplasmic reticulum | Endoplasmic reticulum with attached ribosomes on its cytoplasmic surface; site of synthesis for proteins destined for secretion or membrane insertion. |
| smooth endoplasmic reticulum | Endoplasmic reticulum that functions in the detoxification of cells and lipid synthesis. |
| subcellular component | Structures within a cell that perform specific functions, including both membrane-bound organelles and non-membrane structures. |
| transport vesicle | Membrane-bound structures that are part of the endomembrane system and transport materials between organelles. |
| turgor pressure | The pressure maintained in plant cells by a large vacuole through nutrient and water storage. |
| vacuole | Membrane-bound sacs that store cellular materials and play various roles in plant and animal cells. |
| Term | Definition |
|---|---|
| heat exchange | The transfer of thermal energy between an organism's body and the surrounding environment; rate decreases as organism size increases. |
| membrane folds | Infoldings of the cell membrane that increase surface area to facilitate more efficient material exchange in complex cells. |
| metabolic rate | The rate at which an organism uses energy; typically higher per unit body mass in smaller organisms than in larger organisms. |
| nutrient exchange | The process by which cells obtain necessary nutrients from the environment. |
| plasma membrane | The selectively permeable membrane that surrounds the cell, composed of phospholipids, proteins, and other molecules that regulate what enters and exits the cell. |
| surface area-to-volume ratio | The relationship between the total surface area and the total volume of a cell or organism; affects the efficiency of material exchange with the environment. |
| thermal energy exchange | The transfer of heat energy between an organism and its environment. |
| waste products | Byproducts of cellular metabolism that must be eliminated from cells or organisms. |
| Term | Definition |
|---|---|
| cholesterol | A steroid molecule found in the plasma membranes of vertebrate animals that regulates membrane fluidity and stability. |
| cytosol | The aqueous interior of the cell where hydrophilic protein regions may be exposed. |
| embedded protein | Proteins that are integrated into or span across the phospholipid bilayer of the cell membrane. |
| fatty acid | Organic compounds consisting of a carboxyl group attached to a long hydrocarbon chain; can be saturated or unsaturated. |
| fluid mosaic model | A model describing the plasma membrane as a flexible structure composed of a phospholipid bilayer with embedded and peripheral proteins that can move laterally within the membrane. |
| glycolipid | A lipid with carbohydrate chains attached, found in the plasma membrane and involved in cell recognition. |
| glycoprotein | A protein with carbohydrate chains attached, found in the plasma membrane and involved in cell recognition and signaling. |
| hydrophilic | Water-loving; referring to polar molecules or regions that interact favorably with water. |
| hydrophobic | Water-repelling; referring to nonpolar molecules or regions that do not interact favorably with water. |
| nonpolar | Referring to molecules or groups with even distribution of electrical charge, making them hydrophobic. |
| phosphate | A chemical group that is part of the nucleotide structure and forms covalent bonds between nucleotides in a nucleic acid strand. |
| phospholipid | Amphipathic molecules with hydrophilic phosphate heads and hydrophobic fatty acid tails that form the basic structure of the cell membrane. |
| plasma membrane | The selectively permeable membrane that surrounds the cell, composed of phospholipids, proteins, and other molecules that regulate what enters and exits the cell. |
| polar | Referring to molecules or groups with uneven distribution of electrical charge, making them hydrophilic. |
| protein | Macromolecules composed of amino acids linked together, containing carbon, hydrogen, oxygen, nitrogen, and often sulfur, that perform diverse functions in cells. |
| steroid | Lipids with a four-ring carbon structure that function as hormones supporting growth, development, energy metabolism, and homeostasis. |
| Term | Definition |
|---|---|
| cell wall | A rigid structural layer outside the cell membrane that provides support, maintains cell shape, and acts as a permeability barrier in bacteria, archaea, fungi, and plants. |
| hydrocarbon tail | The nonpolar, hydrophobic portions of phospholipids that form the interior of the membrane and prevent ion and polar molecule movement. |
| hydrophilic substance | Water-loving polar molecules and ions that cannot easily cross the hydrophobic membrane interior and require transport proteins or channels. |
| hydrophobic interior | The nonpolar region in the middle of the phospholipid bilayer that repels water and polar molecules. |
| ion | Charged particles that cannot freely cross the hydrophobic membrane interior and require transport proteins or channels for movement. |
| nonpolar molecule | Molecules that lack a net electric charge and can pass freely across the hydrophobic interior of the membrane. |
| osmotic lysis | The rupture of a cell membrane due to water entering the cell in a hypotonic environment; prevented by the cell wall in plant cells, bacteria, archaea, and fungi. |
| permeability barrier | A selective barrier that controls which substances can pass between the internal and external cellular environments. |
| phospholipid | Amphipathic molecules with hydrophilic phosphate heads and hydrophobic fatty acid tails that form the basic structure of the cell membrane. |
| plasma membrane | The selectively permeable membrane that surrounds the cell, composed of phospholipids, proteins, and other molecules that regulate what enters and exits the cell. |
| polar molecule | Molecules with uneven distribution of electrical charge that generally cannot cross the hydrophobic membrane interior without assistance. |
| selective permeability | The property of a membrane that allows certain substances to pass through while restricting the passage of others. |
| structural boundary | The physical barrier provided by the cell wall that defines and maintains the shape and integrity of the cell. |
| transport protein | Embedded membrane proteins that facilitate the movement of hydrophilic substances across the membrane. |
| Term | Definition |
|---|---|
| active transport | The movement of ions and molecules across a membrane against their concentration gradient, requiring metabolic energy from ATP. |
| concentration gradient | A difference in the concentration of a substance across a membrane, with higher concentration on one side and lower concentration on the other. |
| endocytosis | A process in which a cell takes in large molecules and particulate matter by folding the plasma membrane inward to form vesicles that engulf external material. |
| exocytosis | A process in which internal vesicles fuse with the plasma membrane to release large molecules and other materials from the cell. |
| metabolic energy | Energy derived from cellular metabolism, typically in the form of ATP, used to power cellular processes. |
| passive transport | The net movement of molecules from regions of high concentration to regions of low concentration without the direct input of metabolic energy. |
| plasma membrane | The selectively permeable membrane that surrounds the cell, composed of phospholipids, proteins, and other molecules that regulate what enters and exits the cell. |
| selective permeability | The property of a membrane that allows certain substances to pass through while restricting the passage of others. |
| solute | A substance dissolved in a solvent to form a solution; the component present in smaller amount in a solution. |
| vesicle | Small membrane-bound sacs that transport and store materials within or between cells. |
| water balance | The regulation of water movement into and out of cells to maintain proper cellular function and organism homeostasis. |
| Term | Definition |
|---|---|
| aquaporins | Channel proteins that facilitate the rapid transport of water molecules across cell membranes. |
| channel protein | Membrane proteins that form pores or channels allowing specific ions or molecules to pass through the plasma membrane. |
| charged ion | Atoms or molecules that have gained or lost electrons and carry an electrical charge, such as sodium (Na⁺) and potassium (K⁺). |
| concentration gradient | A difference in the concentration of a substance across a membrane, with higher concentration on one side and lower concentration on the other. |
| facilitated diffusion | The passive transport of substances across a membrane through protein channels or carriers, requiring no energy input but moving down the concentration gradient. |
| membrane polarization | The development of an electrical charge difference across a membrane caused by the movement of ions. |
| plasma membrane | The selectively permeable membrane that surrounds the cell, composed of phospholipids, proteins, and other molecules that regulate what enters and exits the cell. |
| polar molecule | Molecules with uneven distribution of electrical charge that generally cannot cross the hydrophobic membrane interior without assistance. |
| transport protein | Embedded membrane proteins that facilitate the movement of hydrophilic substances across the membrane. |
| Term | Definition |
|---|---|
| central vacuole | A large organelle in plant cells that stores water and solutes, playing a role in maintaining turgor pressure and osmoregulation. |
| concentration gradient | A difference in the concentration of a substance across a membrane, with higher concentration on one side and lower concentration on the other. |
| contractile vacuole | An organelle in protists that collects and expels excess water to maintain osmotic balance. |
| homeostasis | The maintenance of stable internal environmental conditions in an organism despite external and internal changes. |
| hypertonic | A solution with a higher solute concentration relative to another solution, causing water to move out of the cell. |
| hypotonic | A solution with a lower solute concentration relative to another solution, causing water to move into the cell. |
| isotonic | A solution with the same solute concentration as another solution, resulting in no net movement of water across the membrane. |
| osmolarity | The concentration of solutes in a solution, which determines the direction of water movement across membranes. |
| osmoregulation | The process by which organisms maintain water balance and control their internal solute composition and water potential. |
| osmoregulatory mechanism | Physiological processes that organisms use to maintain water balance and regulate internal solute composition. |
| osmosis | The movement of water across a semipermeable membrane from regions of high water potential to regions of low water potential. |
| pressure potential | The component of water potential representing the physical pressure exerted on water in a cell, often due to cell wall rigidity. |
| solute concentration | The amount of dissolved solutes per unit volume of solution, which affects water movement across membranes. |
| solute potential | The component of water potential that represents the effect of dissolved solutes in lowering the potential energy of water. |
| water balance | The regulation of water movement into and out of cells to maintain proper cellular function and organism homeostasis. |
| water potential | The potential energy of water in a system, determined by pressure potential and solute potential, that drives water movement. |
| Term | Definition |
|---|---|
| active transport | The movement of ions and molecules across a membrane against their concentration gradient, requiring metabolic energy from ATP. |
| ATPase | An enzyme that catalyzes the breakdown of ATP to release energy for active transport and other cellular processes. |
| electrochemical gradient | The combined effect of the concentration gradient and electrical potential difference across a membrane that influences ion movement. |
| membrane potential | The electrical potential difference across a cell membrane, maintained by the Na⁺/K⁺ pump and other ion pumps. |
| membrane protein | Proteins embedded in or attached to the cell membrane that facilitate the transport of molecules and ions across the membrane. |
| Na⁺/K⁺ pump | An active transport protein that uses ATP to move sodium ions out of the cell and potassium ions into the cell, maintaining the membrane potential. |
| Term | Definition |
|---|---|
| compartmentalization | The division of the eukaryotic cell into distinct membrane-bound regions that separate different metabolic processes and enzymatic reactions. |
| enzymatic reaction | Chemical reactions catalyzed by enzymes that occur within specific cellular compartments to facilitate metabolic processes. |
| eukaryotic cell | Cells that contain a membrane-bound nucleus and internal membrane-bound organelles, found in animals, plants, fungi, and protists. |
| internal membrane | Membranes within eukaryotic cells that divide the cell into compartments with specialized functions. |
| intracellular metabolic process | Chemical reactions and pathways that occur within the cell to build up or break down molecules for energy and biosynthesis. |
| membrane-bound organelle | Specialized structures within eukaryotic cells enclosed by a membrane that perform specific cellular functions. |
| membrane-bound structure | Organelles and compartments in eukaryotic cells that are enclosed by a lipid bilayer membrane, separating their contents from the cytoplasm. |
| organelle | Membrane-bound or non-membrane-bound structures within eukaryotic cells that perform specific cellular functions. |
| surface area | The total area of a membrane available for chemical reactions and cellular processes to occur. |
| Term | Definition |
|---|---|
| activation energy | The minimum energy required for a chemical reaction to proceed; enzymes lower this energy barrier to facilitate reactions. |
| active site | The specific region on an enzyme where the substrate binds and the chemical reaction is catalyzed. |
| biological catalysts | Substances that speed up biological reactions without being consumed in the process; enzymes are the primary biological catalysts in cells. |
| enzyme | Proteins that act as biological catalysts to speed up chemical reactions in cells by lowering activation energy. |
| enzyme-substrate complex | The temporary complex formed when a substrate binds to the active site of an enzyme during a catalyzed reaction. |
| substrate | The molecule or substance upon which an enzyme acts during a chemical reaction. |
| Term | Definition |
|---|---|
| active site | The specific region on an enzyme where the substrate binds and the chemical reaction is catalyzed. |
| allosteric site | A binding site on an enzyme other than the active site, where regulatory molecules can bind to affect enzyme activity. |
| cellular environment | The internal conditions of a cell, including temperature, pH, and concentrations of molecules, that affect enzyme function. |
| chemical environment | The composition of substances surrounding an enzyme that can affect its structure and function. |
| collision frequency | The rate at which enzyme and substrate molecules encounter each other in solution, affecting the rate of enzymatic reaction. |
| competitive inhibitor | A molecule that binds reversibly to the active site of an enzyme, competing with substrate for binding and reducing enzyme activity. |
| denaturation | The disruption of a protein's three-dimensional structure, causing loss of its biological function. |
| enzymatic reaction rate | The speed at which an enzyme catalyzes the conversion of substrate to product. |
| enzyme | Proteins that act as biological catalysts to speed up chemical reactions in cells by lowering activation energy. |
| enzyme activity | The rate at which an enzyme catalyzes a biochemical reaction under specific cellular conditions. |
| enzyme efficiency | The rate at which an enzyme catalyzes a reaction under given conditions. |
| enzyme function | The ability of an enzyme to catalyze specific biochemical reactions efficiently. |
| hydrogen bond | Weak attractive forces between a hydrogen atom bonded to an electronegative atom and another electronegative atom, occurring between or within biological molecules. |
| noncompetitive inhibitor | A molecule that binds to an allosteric site on an enzyme, changing the enzyme's shape and reducing its activity without competing with substrate. |
| optimal pH | The pH at which an enzyme exhibits maximum catalytic activity and efficiency. |
| optimal temperature | The temperature at which an enzyme exhibits maximum catalytic activity and efficiency. |
| product | The molecule produced as a result of an enzymatic reaction. |
| product concentration | The relative amount of product molecules present in a solution, which can affect the efficiency of an enzymatic reaction. |
| protein structure | The three-dimensional arrangement of amino acids in a protein, which determines its properties and function. |
| reversible denaturation | The process by which a denatured enzyme can regain its original structure and catalytic activity when environmental conditions are restored. |
| substrate | The molecule or substance upon which an enzyme acts during a chemical reaction. |
| substrate concentration | The relative amount of substrate molecules available for an enzyme to catalyze, which affects the rate of enzymatic reaction. |
| temperature | An environmental factor that affects the kinetic energy and collision frequency of molecules, influencing enzyme activity. |
| Term | Definition |
|---|---|
| cellular processes | Biochemical reactions and activities that occur within cells to maintain life and carry out functions. |
| common ancestry | The concept that all organisms share a common evolutionary origin and are related through descent from earlier ancestral species. |
| conserved process | Biological processes that are maintained relatively unchanged across different organisms and evolutionary time, indicating shared ancestry. |
| core metabolic pathways | Essential biochemical sequences that are conserved across different organisms and domains of life, such as glycolysis and oxidative phosphorylation. |
| coupled reactions | Cellular processes where energy-releasing reactions are linked to energy-requiring reactions to transfer energy efficiently. |
| domain | The three major categories of life (Archaea, Bacteria, and Eukarya) that represent the highest taxonomic rank in biological classification. |
| energy | The capacity to do work or cause change in living systems; required by all organisms to maintain order and power cellular processes. |
| energy transfer | The movement of energy from one form or location to another through sequential reactions in metabolic pathways. |
| first law of thermodynamics | The principle that energy cannot be created or destroyed, only transformed from one form to another. |
| glycolysis | A biochemical pathway in the cytosol that breaks down glucose and releases energy to form ATP, NADH, and pyruvate. |
| living systems | Organized biological entities that require energy input to maintain their structure and functions. |
| metabolic pathway | A series of sequential chemical reactions in cells where the product of one reaction serves as the reactant for the next reaction. |
| order | The organized, structured state of a living system that requires continuous energy input to maintain. |
| oxidative phosphorylation | The synthesis of ATP coupled to electron transport in the electron transport chain during aerobic cellular respiration. |
| second law of thermodynamics | The principle that in any energy transformation, some energy is lost as heat and disorder (entropy) in the universe increases. |
| Term | Definition |
|---|---|
| adenosine triphosphate | The primary energy currency of cells that powers cellular functions. |
| ADP | Adenosine diphosphate; a molecule that is phosphorylated to form ATP during oxidative phosphorylation. |
| ATP synthase | A membrane-bound enzyme that uses the proton gradient to drive the synthesis of ATP from ADP and inorganic phosphate. |
| Calvin cycle | The light-independent reactions of photosynthesis that use ATP and NADPH to produce carbohydrates from carbon dioxide in the stroma. |
| carbohydrates | Biological molecules composed of carbon, hydrogen, and oxygen that serve as a primary source of energy and structural support in living organisms. |
| carbon fixation | The process in the Calvin cycle that incorporates carbon dioxide into organic molecules. |
| chemiosmosis | The process by which the flow of protons across a membrane through ATP synthase drives ATP synthesis. |
| chlorophyll | A pigment in chloroplasts that absorbs light energy and transfers electrons to higher energy levels in photosystems. |
| chloroplast | An organelle in plant cells where photosynthesis occurs, containing thylakoids and stroma. |
| cyanobacteria | Prokaryotic photosynthetic organisms responsible for producing an oxygenated atmosphere through photosynthesis. |
| electrochemical gradient | The combined effect of the concentration gradient and electrical potential difference across a membrane that influences ion movement. |
| electron transport | A series of protein complexes in thylakoid membranes that transfer electrons and help generate ATP and NADPH during the light reactions. |
| electron transport chain | A series of protein complexes in membranes that transfer electrons and establish an electrochemical gradient to generate ATP during photosynthesis and cellular respiration. |
| grana | Stacks of thylakoid membranes organized within the chloroplast where light reactions of photosynthesis occur. |
| inorganic phosphate | A free phosphate group (Pi) that is added to ADP to form ATP during ATP synthesis. |
| light reactions | The light-dependent stage of photosynthesis that occurs in the thylakoid membrane and produces ATP and NADPH. |
| NADP⁺ | An electron carrier molecule that accepts electrons during photosynthesis and is reduced to NADPH to carry energy for the Calvin cycle. |
| NADPH | The reduced form of NADP⁺ that carries electrons and energy from the light reactions to power the Calvin cycle. |
| oxidation/reduction reactions | Chemical reactions in which electrons are transferred between molecules, occurring in the electron transport chain during photosynthesis. |
| photophosphorylation | The synthesis of ATP from ADP and inorganic phosphate using energy from the proton gradient established during the light reactions of photosynthesis. |
| photosynthesis | The series of reactions that use carbon dioxide, water, and light energy to produce carbohydrates and oxygen, allowing organisms to capture and store energy from the sun. |
| photosystem | Organized complexes of chlorophyll pigments and proteins in thylakoid membranes that capture light energy during the light reactions. |
| photosystem I | A light-harvesting complex embedded in the thylakoid membrane that uses light energy to boost electrons to a higher energy level and reduce NADP⁺ to NADPH. |
| photosystem II | A light-harvesting complex embedded in the thylakoid membrane that uses light energy to boost electrons and splits water to replace lost electrons. |
| prokaryotic photosynthesis | Photosynthetic processes in prokaryotic organisms, particularly cyanobacteria, that were the evolutionary foundation for eukaryotic photosynthesis. |
| proton gradient | A difference in proton concentration across a membrane, with higher concentration on one side than the other. |
| stroma | The fluid-filled space inside the chloroplast where the Calvin cycle occurs. |
| thylakoid | Membrane structures within the chloroplast that contain chlorophyll pigments and electron transport proteins, where light reactions occur. |
| thylakoid membrane | The membrane system within chloroplasts where light-dependent reactions of photosynthesis occur, containing photosystems and electron transport chains. |
| water splitting | The photolysis of water molecules during photosystem II that releases electrons, protons, and oxygen. |
| Term | Definition |
|---|---|
| adenosine triphosphate | The primary energy currency of cells that powers cellular functions. |
| ADP | Adenosine diphosphate; a molecule that is phosphorylated to form ATP during oxidative phosphorylation. |
| aerobic cellular respiration | The metabolic pathway that uses oxygen as the terminal electron acceptor to generate ATP from biological macromolecules. |
| ATP synthase | A membrane-bound enzyme that uses the proton gradient to drive the synthesis of ATP from ADP and inorganic phosphate. |
| biological macromolecules | Large organic molecules such as carbohydrates, lipids, and proteins that store chemical energy used in cellular respiration. |
| carbon dioxide | A gas released during the Krebs cycle as organic molecules are oxidized. |
| cellular respiration | The metabolic process by which cells break down biological macromolecules to release energy and synthesize ATP. |
| chemiosmosis | The process by which the flow of protons across a membrane through ATP synthase drives ATP synthesis. |
| decoupling | The separation of oxidative phosphorylation from electron transport, resulting in heat generation instead of ATP synthesis. |
| electrochemical gradient | The combined effect of the concentration gradient and electrical potential difference across a membrane that influences ion movement. |
| electron acceptor | A molecule that receives electrons during a redox reaction; oxygen is the terminal electron acceptor in aerobic respiration. |
| electron transport chain | A series of protein complexes in membranes that transfer electrons and establish an electrochemical gradient to generate ATP during photosynthesis and cellular respiration. |
| endothermic organisms | Organisms that generate and regulate their own body heat through metabolic processes. |
| enzyme-catalyzed reactions | Chemical reactions in cells that are accelerated by enzymes, which act as biological catalysts. |
| eukaryotes | Organisms whose cells contain a membrane-bound nucleus and other membrane-bound organelles. |
| FAD | A coenzyme that accepts electrons during the Krebs cycle, forming FADH₂. |
| FADH₂ | Flavin adenine dinucleotide (reduced form); an electron carrier that delivers electrons to the electron transport chain. |
| fermentation | An anaerobic metabolic process that regenerates ATP and NAD+ without using the electron transport chain or oxygen. |
| glucose | A six-carbon sugar whose energy is released through cellular respiration to power cellular functions. |
| glycolysis | A biochemical pathway in the cytosol that breaks down glucose and releases energy to form ATP, NADH, and pyruvate. |
| heat | Thermal energy generated when oxidative phosphorylation is uncoupled from electron transport in cellular respiration. |
| inner mitochondrial membrane | The innermost membrane of the mitochondrion that contains the electron transport chain and is the site of ATP synthesis. |
| inorganic phosphate | A free phosphate group (Pi) that is added to ADP to form ATP during ATP synthesis. |
| intermembrane space | The region between the inner and outer mitochondrial membranes where protons accumulate during the electron transport chain. |
| Krebs cycle | A biochemical cycle in the mitochondrial matrix that oxidizes pyruvate, releases CO₂, generates ATP, and transfers electrons via NAD⁺ and FAD. |
| lactic acid | An organic molecule produced during fermentation in the absence of oxygen. |
| mitochondria | Membrane-bound organelles in eukaryotic cells that are the primary site of aerobic cellular respiration and ATP synthesis. |
| mitochondrial matrix | The innermost compartment of the mitochondrion where the Krebs cycle occurs. |
| mitochondrion | An organelle where pyruvate is oxidized and ATP is generated through the Krebs cycle and electron transport chain. |
| NAD⁺ | A coenzyme that accepts electrons during glycolysis and the Krebs cycle, forming NADH. |
| NADH | Nicotinamide adenine dinucleotide (reduced form); an electron carrier that delivers electrons to the electron transport chain. |
| oxidation | The process of losing electrons, which occurs when pyruvate and other molecules are broken down in the Krebs cycle. |
| oxidation-reduction reactions | Chemical reactions involving the transfer of electrons between molecules, where one molecule is oxidized and another is reduced. |
| oxidative phosphorylation | The synthesis of ATP coupled to electron transport in the electron transport chain during aerobic cellular respiration. |
| oxygen | An element that is a prevalent component of biological molecules and is found in carbohydrates, lipids, proteins, and nucleic acids. |
| plasma membrane | The selectively permeable membrane that surrounds the cell, composed of phospholipids, proteins, and other molecules that regulate what enters and exits the cell. |
| prokaryotes | Single-celled organisms without a membrane-bound nucleus, such as bacteria and archaea. |
| proton gradient | A difference in proton concentration across a membrane, with higher concentration on one side than the other. |
| pyruvate | A three-carbon molecule produced from glycolysis that is transported to the mitochondrion for further oxidation. |
| Term | Definition |
|---|---|
| antigen-presenting cells | Immune cells that display antigens on their surface to communicate with and activate other immune cells like helper T-cells. |
| cell communication | The process by which cells transmit information to and receive information from other cells to coordinate activities and responses. |
| cell-to-cell contact | Direct physical interaction between cells that allows them to communicate and influence each other's behavior. |
| chemical signaling | A form of cell communication that occurs when cells release chemical signals that travel through the environment to affect distant cells. |
| direct contact | A form of cell communication that occurs when cells physically touch one another to exchange signals or information. |
| estrogen | A steroid hormone that travels long distances through the bloodstream to regulate female sexual characteristics and reproductive function. |
| helper T-cells | Immune cells that communicate with antigen-presenting cells and coordinate immune responses by signaling other immune cells. |
| human growth hormone | A hormone secreted by the pituitary gland that travels long distances to promote growth and metabolism in target tissues. |
| insulin | A hormone that helps regulate blood sugar levels as part of negative feedback mechanisms. |
| killer T-cells | Immune cells that interact with other cells through direct contact to identify and destroy infected or abnormal cells. |
| local regulators | Signaling molecules that target cells in the vicinity of the signal-emitting cell, enabling short-distance cell communication. |
| morphogens | Signaling molecules that diffuse through embryonic tissues and establish concentration gradients to direct cell differentiation and development. |
| neurotransmitters | Chemical messengers released by neurons that transmit signals across synapses to target cells over short distances. |
| quorum sensing | A form of bacterial communication in which microbes regulate gene expression and behavior in response to population density through chemical messengers. |
| testosterone | A steroid hormone that travels long distances through the bloodstream to regulate male sexual characteristics and reproductive function. |
| thyroid hormones | Hormones produced by the thyroid gland that travel long distances to regulate metabolism and growth in target cells. |
| Term | Definition |
|---|---|
| cellular response | The change in cell behavior or function that results from signal transduction, such as gene expression or cell division. |
| cyclic AMP | A second messenger molecule (cAMP) that relays and amplifies intracellular signals. |
| G protein-coupled receptor | A type of receptor protein in eukaryotes that uses G proteins to relay signals inside the cell. |
| hormone | A signaling molecule that travels through the bloodstream to reach distant target cells. |
| intracellular domain | The portion of a receptor protein located inside the cell that changes shape upon ligand binding to initiate signal transduction. |
| ligand | A chemical messenger that binds to a receptor protein to initiate a signal transduction pathway. |
| ligand-binding domain | The region of a receptor protein that recognizes and binds to a specific chemical messenger. |
| ligand-gated channel | An ion channel that opens or closes in response to ligand binding. |
| phosphorylation | The addition of a phosphate group to a protein, a key protein modification in signal transduction pathways. |
| phosphorylation cascade | A series of sequential phosphorylation events where one phosphorylated protein activates the next, amplifying a cellular signal. |
| protein modification | A chemical change made to a protein that alters its structure or function during signal transduction. |
| receptor protein | A protein that binds to signaling molecules and initiates a signal transduction pathway by undergoing a conformational change. |
| second messenger | A small molecule, such as cAMP, that relays and amplifies signals from a receptor inside the cell. |
| signal amplification | The process by which a signaling cascade increases the strength or magnitude of an incoming signal. |
| signal reception | The initial step in signal transduction where a cell receives a signal, typically through a receptor protein. |
| signal transduction pathway | A series of molecular events that transmits a signal from outside a cell to inside, resulting in a cellular response. |
| signaling cascade | A series of molecular interactions that relay and amplify signals from a receptor to produce a cellular response. |
| Term | Definition |
|---|---|
| cell function | The specific activities and processes that a cell performs to maintain life and respond to its environment. |
| cellular response | The change in cell behavior or function that results from signal transduction, such as gene expression or cell division. |
| chemical messengers | Signaling molecules used by cells to communicate with other cells and coordinate cellular responses. |
| cytokines | Signaling molecules that regulate gene expression to allow for cell replication and division. |
| downstream components | The proteins and molecules in a signal transduction pathway that are activated or inhibited after the initial signal is received by a receptor. |
| epinephrine | A hormone and neurotransmitter that triggers cellular responses including the breakdown of glycogen for energy mobilization. |
| ethylene | A plant hormone whose levels regulate the production of enzymes involved in fruit ripening. |
| gene expression | The process by which information from a gene is used to synthesize functional gene products, typically proteins, which can be influenced by environmental conditions. |
| glycogen breakdown | The metabolic process of breaking down glycogen into glucose in response to cellular signals such as epinephrine. |
| HOX genes | Genes that regulate the development of animal body plans by controlling the identity and positioning of body segments during embryonic development. |
| mutation | An alteration in a DNA sequence that can cause changes in the type or amount of protein produced and the resulting phenotype. |
| phenotype | The observable physical and biochemical characteristics of an organism, determined by both genetic and environmental factors. |
| pheromones | Chemical signals released by organisms that trigger specific behavioral or developmental responses in other organisms of the same species. |
| programmed cell death | Programmed cell death, a controlled process in which a cell actively participates in its own destruction. |
| quorum sensing | A form of bacterial communication in which microbes regulate gene expression and behavior in response to population density through chemical messengers. |
| receptor protein | A protein that binds to signaling molecules and initiates a signal transduction pathway by undergoing a conformational change. |
| signal transduction pathway | A series of molecular events that transmits a signal from outside a cell to inside, resulting in a cellular response. |
| signaling molecule | A chemical substance that carries a signal from one cell to another, initiating a cellular response through a signal transduction pathway. |
| Term | Definition |
|---|---|
| feedback mechanisms | Biological processes that organisms use to maintain their internal environments in response to changes. |
| glucagon | A hormone that helps regulate blood sugar levels as part of negative feedback mechanisms. |
| homeostasis | The maintenance of stable internal environmental conditions in an organism despite external and internal changes. |
| insulin | A hormone that helps regulate blood sugar levels as part of negative feedback mechanisms. |
| negative feedback | A feedback mechanism that reduces the initial stimulus to maintain homeostasis by returning a system back to its target set point. |
| positive feedback | A feedback mechanism that amplifies responses and moves a variable further away from its initial set point, intensifying the stimulus to produce system change. |
| set point | The target physiological condition that an organism's feedback mechanisms work to maintain or return to. |
| Term | Definition |
|---|---|
| anaphase | The stage of mitosis in which paired sister chromatids separate and spindle fibers pull them toward opposite poles of the cell. |
| asexual reproduction | Reproduction that produces offspring genetically identical to the parent without the fusion of gametes. |
| cell cycle | A highly regulated series of events that controls the growth and reproduction of eukaryotic cells. |
| cell plate | The structure that forms during cytokinesis in plant cells to divide the cytoplasm and create a new cell wall. |
| centromere | The region of a chromosome where sister chromatids are joined and where kinetochores attach. |
| centrosomes | Cellular structures that serve as the main microtubule-organizing centers and move to opposite poles of the cell during mitosis. |
| chromatin | The form in which DNA exists during interphase, consisting of DNA and associated proteins. |
| chromosomes | Structures in eukaryotic cells composed of DNA and proteins that carry genetic information and are transmitted to daughter cells during mitosis. |
| cleavage furrow | The indentation that forms during cytokinesis in animal cells to divide the cytoplasm. |
| cytokinesis | The division of the cytoplasm that occurs after mitosis, resulting in the physical separation of a parent cell into two daughter cells. |
| daughter cells | The two genetically identical cells produced as a result of mitosis. |
| eukaryotic cell | Cells that contain a membrane-bound nucleus and internal membrane-bound organelles, found in animals, plants, fungi, and protists. |
| G0 phase | A stage in which a cell no longer divides but can reenter the cell cycle in response to appropriate cues. |
| G1 phase | The first phase of interphase in which the cell is metabolically active and duplicates organelles and cytosolic components. |
| G2 phase | The second phase of interphase in which protein synthesis occurs, ATP is produced in large quantities, and centrosomes replicate. |
| genome | The complete set of genetic material (DNA) in a cell. |
| interphase | The phase of the cell cycle between successive mitotic divisions during which the cell grows and replicates its DNA. |
| metaphase | The stage of mitosis in which spindle fibers align chromosomes along the equator (metaphase plate) of the cell. |
| mitosis | A process of cell division in eukaryotes that produces two genetically identical daughter cells, each with a complete copy of the parent cell's genome. |
| mitotic spindle | A structure composed of spindle fibers that forms during mitosis and is responsible for separating and moving chromosomes to opposite poles of the cell. |
| nuclear envelope | A membrane-bound component of the endomembrane system that surrounds the nucleus. |
| prophase | The first stage of mitosis in which sister chromatids condense, the mitotic spindle begins to form, and centrosomes move to opposite poles of the cell. |
| S phase | The synthesis phase of interphase in which DNA replicates to form two sister chromatids connected at a centromere. |
| sister chromatids | Two identical copies of a chromosome joined at the centromere, formed after DNA replication. |
| spindle fibers | Protein structures that extend from centrosomes and attach to chromosomes to move them during mitosis. |
| telophase | The final stage of mitosis in which the mitotic spindle breaks down, a new nuclear envelope develops around each set of chromosomes, and the cytoplasm begins to divide. |
| tissue repair | The process by which mitosis generates new cells to replace damaged or worn-out cells in an organism. |
| Term | Definition |
|---|---|
| cancer | A disease resulting from uncontrolled cell division due to disruptions in cell cycle regulation, allowing cells to divide abnormally and form tumors. |
| cell cycle | A highly regulated series of events that controls the growth and reproduction of eukaryotic cells. |
| cell cycle disruptions | Abnormal interruptions or malfunctions in the regulated progression of cell division stages, which can lead to cellular dysfunction or disease. |
| checkpoints | Internal control points in the cell cycle that regulate progression and ensure cells meet specific conditions before advancing to the next phase. |
| cyclin-dependent kinases | Enzymes that are activated by cyclins and phosphorylate target proteins to regulate progression through the cell cycle. |
| cyclins | Regulatory proteins that fluctuate in concentration during the cell cycle and control the timing of cell cycle events. |
| internal controls | Regulatory mechanisms within a cell that monitor conditions and control cell cycle progression. |
| programmed cell death | Programmed cell death, a controlled process in which a cell actively participates in its own destruction. |
| Term | Definition |
|---|---|
| cell plate | The structure that forms during cytokinesis in plant cells to divide the cytoplasm and create a new cell wall. |
| centromere | The region of a chromosome where sister chromatids are joined and where kinetochores attach. |
| centrosomes | Cellular structures that serve as the main microtubule-organizing centers and move to opposite poles of the cell during mitosis. |
| chiasmata | Points where homologous chromosomes physically connect and exchange genetic material during meiosis. |
| chromosomes | Structures in eukaryotic cells composed of DNA and proteins that carry genetic information and are transmitted to daughter cells during mitosis. |
| cleavage furrow | The indentation that forms during cytokinesis in animal cells to divide the cytoplasm. |
| cytokinesis | The division of the cytoplasm that occurs after mitosis, resulting in the physical separation of a parent cell into two daughter cells. |
| daughter cells | The two genetically identical cells produced as a result of mitosis. |
| diploid | A cell or organism containing two complete sets of chromosomes, typically represented as 2n. |
| gamete | A haploid reproductive cell (sperm or egg) produced by meiosis that fuses with another gamete during fertilization. |
| genetic content | The total amount and composition of DNA and genes present in a cell. |
| haploid | A cell or organism containing a single set of chromosomes, typically represented as n. |
| homologous chromosomes | Pairs of chromosomes, one inherited from each parent, that have the same genes at corresponding locations. |
| kinetochore | A protein structure at the centromere where microtubules of the meiotic spindle attach to pull chromatids apart. |
| meiosis | A process of cell division in diploid organisms that produces haploid gamete cells, reducing chromosome number by half for sexual reproduction. |
| meiotic spindle | The structure of microtubules that forms during meiosis to separate chromosomes toward opposite poles of the cell. |
| metaphase plate | The equatorial region of the cell where chromosomes align during metaphase of meiosis. |
| microtubule | Protein filaments that make up the meiotic spindle and pull chromosomes toward opposite poles of the cell. |
| mitosis | A process of cell division in eukaryotes that produces two genetically identical daughter cells, each with a complete copy of the parent cell's genome. |
| nuclear envelope | A membrane-bound component of the endomembrane system that surrounds the nucleus. |
| sister chromatids | Two identical copies of a chromosome joined at the centromere, formed after DNA replication. |
| spindle apparatus | A structure composed of microtubules that forms during cell division and is responsible for moving and separating chromosomes. |
| synapsis | The pairing and alignment of homologous chromosomes during Prophase I of meiosis. |
| Term | Definition |
|---|---|
| crossing over | The exchange of genetic material between non-sister chromatids of homologous chromosomes during prophase I of meiosis. |
| fertilization | The fusion of two gametes to form a diploid zygote, combining genetic material from both parents. |
| gamete | A haploid reproductive cell (sperm or egg) produced by meiosis that fuses with another gamete during fertilization. |
| genetic diversity | The variety of different alleles and genes present within a population or species. |
| haploid | A cell or organism containing a single set of chromosomes, typically represented as n. |
| homologous chromosomes | Pairs of chromosomes, one inherited from each parent, that have the same genes at corresponding locations. |
| maternal chromosomes | Chromosomes inherited from the mother. |
| meiosis | A process of cell division in diploid organisms that produces haploid gamete cells, reducing chromosome number by half for sexual reproduction. |
| meiosis I | The first division of meiosis in which homologous chromosomes separate, reducing the chromosome number from diploid to haploid. |
| meiosis II | The second division of meiosis in which sister chromatids separate, similar to mitosis. |
| non-sister chromatids | Chromatids from different homologous chromosomes that can exchange genetic material during crossing over. |
| nondisjunction | The failure of chromosomes to separate properly during mitosis or meiosis, resulting in changes in chromosome number. |
| paternal chromosomes | Chromosomes inherited from the father. |
| prophase I | The first stage of meiosis I in which homologous chromosomes pair up and crossing over occurs. |
| random assortment | The random distribution of homologous chromosome pairs to daughter cells during meiosis I, contributing to genetic variation. |
| recombination | The process by which genetic material is exchanged between homologous chromosomes, creating new combinations of alleles. |
| sexual reproduction | Reproduction involving the fusion of gametes from two parents, producing genetically diverse offspring. |
| sister chromatids | Two identical copies of a chromosome joined at the centromere, formed after DNA replication. |
| Term | Definition |
|---|---|
| allele | Different versions of a gene that can exist at the same location on a chromosome. |
| autosomal inheritance | Inheritance of traits controlled by genes located on autosomes (non-sex chromosomes). |
| dihybrid cross | A cross between two organisms that differ in two traits controlled by two different genes. |
| diploid | A cell or organism containing two complete sets of chromosomes, typically represented as 2n. |
| dominant allele | An allele that is expressed in the phenotype when present in either homozygous or heterozygous condition. |
| genetic variation | Differences in DNA sequences and alleles that exist within a population. |
| genetically linked | Genes located close together on the same chromosome that tend to be inherited together. |
| genotype | The genetic makeup of an organism; the specific alleles present for each gene. |
| haploid gametes | Sex cells (sperm or egg) that contain half the chromosome number of the parent organism. |
| heterozygous | Having two different alleles for a particular gene. |
| homozygous | Having two identical alleles for a particular gene. |
| Mendel's law of independent assortment | The principle that alleles of different genes assort independently during gamete formation when genes are on different chromosomes. |
| Mendel's laws of segregation | The principle that allele pairs separate during gamete formation, with each gamete receiving one allele for each gene. |
| monohybrid cross | A cross between two organisms that differ in a single trait controlled by one gene. |
| pedigree | A diagram showing the inheritance of a trait through multiple generations of a family. |
| phenotype | The observable physical and biochemical characteristics of an organism, determined by both genetic and environmental factors. |
| Punnett square | A diagram used to predict the genotypes and phenotypes of offspring from a cross between two parents. |
| recessive allele | An allele that is expressed in the phenotype only when present in homozygous condition. |
| sex-linked inheritance | Inheritance of traits controlled by genes located on sex chromosomes. |
| test cross | A cross between an organism expressing a dominant phenotype and a homozygous recessive organism to determine the genotype. |
| zygote | A fertilized egg cell formed from the fusion of two gametes. |
| Term | Definition |
|---|---|
| chloroplast DNA | Genetic material located in chloroplasts that can be inherited independently of nuclear DNA, typically through the maternal lineage in plants. |
| codominance | A pattern of inheritance in which both alleles are fully expressed in the heterozygote, resulting in a phenotype different from either homozygote. |
| deviations from Mendel's model | Patterns of inheritance that do not follow the predicted ratios and rules established by Mendel's laws of inheritance. |
| genetic mapping | The process of determining the relative positions and distances of genes on a chromosome based on recombination frequencies. |
| genetically linked | Genes located close together on the same chromosome that tend to be inherited together. |
| incomplete dominance | A pattern of inheritance in which neither allele is completely dominant, resulting in a blended phenotype in the heterozygote that is intermediate between the two homozygous phenotypes. |
| map distance | The relative distance between two genes on a chromosome, measured in map units and calculated based on the frequency of recombination between them. |
| maternal inheritance | A pattern of inheritance in which traits are transmitted only or primarily through the female parent, typically due to organellar DNA in the egg or ovule. |
| mitochondrial DNA | Genetic material located in mitochondria that can be inherited independently of nuclear DNA, typically through the maternal lineage. |
| non-nuclear inheritance | Inheritance of traits determined by genes located in organelles such as mitochondria and chloroplasts rather than in the nucleus. |
| phenotypic ratios | The proportions of different observable traits in offspring, compared to predicted ratios based on genetic crosses. |
| pleiotropy | A phenomenon in which a single gene influences the expression of multiple, seemingly unrelated traits. |
| sex-linked traits | Traits determined by genes located on sex chromosomes (X or Y), which show inheritance patterns different from autosomal traits. |
| Term | Definition |
|---|---|
| environmental conditions | External factors such as temperature, light, pH, and other physical or chemical factors that influence gene expression and phenotype development. |
| gene expression | The process by which information from a gene is used to synthesize functional gene products, typically proteins, which can be influenced by environmental conditions. |
| genotype | The genetic makeup of an organism; the specific alleles present for each gene. |
| phenotype | The observable physical and biochemical characteristics of an organism, determined by both genetic and environmental factors. |
| phenotypic plasticity | The ability of a single genotype to produce different phenotypes in response to different environmental conditions. |
| Term | Definition |
|---|---|
| adenine | A purine nitrogenous base found in both DNA and RNA that pairs with thymine in DNA or uracil in RNA. |
| base pairing | The specific pairing of nitrogenous bases between DNA strands (A-T and C-G) or in RNA (A-U). |
| circular chromosomes | Ring-shaped DNA structures typically found in prokaryotic organisms that contain genetic information. |
| cytosine | A pyrimidine nitrogenous base found in both DNA and RNA that pairs with guanine. |
| DNA molecules | Deoxyribonucleic acid molecules that store genetic information in living organisms. |
| eukaryotes | Organisms whose cells contain a membrane-bound nucleus and other membrane-bound organelles. |
| guanine | A purine nitrogenous base found in both DNA and RNA that pairs with cytosine. |
| hereditary information | Genetic material passed from parent organisms to offspring that determines inherited traits. |
| hereditary material | Genetic material that is passed from parent organisms to offspring and carries the instructions for life. |
| histones | Proteins around which DNA wraps to condense and organize chromosomes in eukaryotic cells. |
| linear chromosomes | Chromosomes with defined endpoints found in eukaryotic cell nuclei, as opposed to the circular chromosomes found in prokaryotes. |
| nucleic acid | Macromolecules composed of nucleotides containing carbon, hydrogen, oxygen, nitrogen, and phosphorus that store and transmit genetic information. |
| nucleotide | The monomer unit of nucleic acids, consisting of a five-carbon sugar, a phosphate group, and a nitrogenous base. |
| plasmids | Small, circular, extra-chromosomal DNA molecules found in prokaryotes and eukaryotes that carry genetic information. |
| prokaryotes | Single-celled organisms without a membrane-bound nucleus, such as bacteria and archaea. |
| purines | Nitrogenous bases with a double ring structure; includes adenine and guanine. |
| pyrimidines | Nitrogenous bases with a single ring structure; includes cytosine, thymine, and uracil. |
| RNA molecules | Ribonucleic acid molecules that can store and transmit genetic information in some organisms. |
| thymine | A pyrimidine nitrogenous base found in DNA that pairs with adenine. |
| uracil | A pyrimidine nitrogenous base found in RNA that pairs with adenine. |
| Term | Definition |
|---|---|
| 5' to 3' direction | The direction in which DNA is synthesized, from the 5' carbon of one sugar to the 3' carbon of the next sugar in the phosphate backbone. |
| complementary DNA | A newly synthesized strand of DNA that is formed based on the base-pairing rules with the template strand. |
| DNA polymerase | An enzyme that synthesizes new DNA strands by adding nucleotides in the 5' to 3' direction. |
| DNA replication | The process by which DNA makes an exact copy of itself, which can be subject to errors that cause mutations. |
| genetic information | The hereditary instructions encoded in DNA that direct the synthesis of proteins and determine organism traits. |
| helicase | An enzyme that unwinds the double helix structure of DNA by breaking hydrogen bonds between base pairs during replication. |
| lagging strand | The strand of DNA synthesized discontinuously in short fragments (Okazaki fragments) in the 5' to 3' direction during replication. |
| leading strand | The strand of DNA synthesized continuously in the 5' to 3' direction during replication. |
| ligase | An enzyme that joins DNA fragments together by forming phosphodiester bonds between adjacent nucleotides on the lagging strand. |
| replication fork | The Y-shaped structure formed during DNA replication where the double helix unwinds and new strands are synthesized. |
| RNA primer | A short RNA sequence synthesized by primase that provides the 3'-OH group required for DNA polymerase to begin DNA synthesis. |
| semiconservative replication | A mechanism of DNA replication in which each new DNA molecule consists of one original strand and one newly synthesized complementary strand. |
| template strand | The original strand of DNA that serves as a pattern for synthesizing a new complementary strand during replication. |
| topoisomerase | An enzyme that relieves tension and relaxes supercoiling in DNA ahead of the replication fork. |
| Term | Definition |
|---|---|
| 3' to 5' direction | The direction in which RNA polymerase reads the template DNA strand during transcription. |
| 5' to 3' direction | The direction in which DNA is synthesized, from the 5' carbon of one sugar to the 3' carbon of the next sugar in the phosphate backbone. |
| alternative splicing | The process by which different combinations of exons are joined together during mRNA processing, producing multiple versions of mature mRNA from a single gene. |
| anticodon | A three-base sequence on tRNA that base pairs with a complementary codon on mRNA during translation. |
| codon | A sequence of three nucleotides on mRNA that specifies a particular amino acid or stop signal during translation. |
| exon | A coding segment of a eukaryotic gene that is retained in the mature mRNA molecule after RNA processing. |
| genetic information | The hereditary instructions encoded in DNA that direct the synthesis of proteins and determine organism traits. |
| guanosine triphosphate cap | A modified guanosine nucleotide structure added to the 5' end of eukaryotic mRNA that aids in ribosomal recognition. |
| intron | A non-coding segment of a eukaryotic gene that is removed from the mRNA transcript during RNA processing. |
| poly-A tail | A string of adenine nucleotides added to the 3' end of eukaryotic mRNA that increases mRNA stability. |
| primary peptide sequence | The initial linear arrangement of amino acids in a protein as determined by the mRNA codon sequence during translation. |
| ribosome | The cellular structure composed of rRNA and proteins that catalyzes the synthesis of polypeptides during translation. |
| RNA polymerase | An enzyme that catalyzes the synthesis of RNA by reading a DNA template strand and linking RNA bases in sequence. |
| RNA processing | A series of enzyme-mediated modifications to eukaryotic mRNA transcripts, including capping, polyadenylation, and splicing. |
| template strand | The original strand of DNA that serves as a pattern for synthesizing a new complementary strand during replication. |
| transcription | The process by which RNA polymerase synthesizes RNA molecules using a DNA template strand. |
| transfer RNA | An RNA molecule that binds specific amino acids and uses anticodon sequences to recognize and pair with mRNA codons during translation. |
| translation | The process by which mRNA is decoded by ribosomes to synthesize a polypeptide chain. |
| Term | Definition |
|---|---|
| amino acid | Organic molecules that serve as the building blocks of proteins, each composed of a central carbon atom bonded to a hydrogen atom, a carboxyl group, an amine group, and a variable R group. |
| codon | A sequence of three nucleotides on mRNA that specifies a particular amino acid or stop signal during translation. |
| elongation | The stage of translation in which amino acids are sequentially added to the growing polypeptide chain. |
| eukaryotic | Referring to organisms that have a membrane-bound nucleus and organelles, such as animals, plants, and fungi. |
| genetic code | The set of rules by which nucleotide sequences in mRNA are translated into amino acid sequences in proteins. |
| genotype | The genetic makeup of an organism; the specific alleles present for each gene. |
| initiation | The first stage of translation in which the ribosome assembles on the mRNA at the start codon. |
| messenger RNA | The RNA molecule that carries genetic information from DNA and serves as the template for protein synthesis. |
| phenotype | The observable physical and biochemical characteristics of an organism, determined by both genetic and environmental factors. |
| polypeptide | A chain of amino acids linked together by peptide bonds. |
| prokaryotic | Referring to organisms that lack a membrane-bound nucleus and organelles, such as bacteria. |
| protein | Macromolecules composed of amino acids linked together, containing carbon, hydrogen, oxygen, nitrogen, and often sulfur, that perform diverse functions in cells. |
| retrovirus | A virus that uses reverse transcriptase to convert its RNA genome into DNA for integration into the host genome. |
| reverse transcriptase | An enzyme that synthesizes DNA from an RNA template, used by retroviruses to convert their RNA genome to DNA. |
| ribosomal RNA | The RNA component of the ribosome that catalyzes peptide bond formation. |
| ribosome | The cellular structure composed of rRNA and proteins that catalyzes the synthesis of polypeptides during translation. |
| rough endoplasmic reticulum | Endoplasmic reticulum with attached ribosomes on its cytoplasmic surface; site of synthesis for proteins destined for secretion or membrane insertion. |
| start codon | The codon AUG where translation begins, coding for the amino acid methionine. |
| stop codon | A codon that signals the termination of translation and the release of the completed polypeptide chain. |
| termination | The final stage of translation in which the ribosome releases the completed polypeptide chain. |
| transcription | The process by which RNA polymerase synthesizes RNA molecules using a DNA template strand. |
| transfer RNA | An RNA molecule that binds specific amino acids and uses anticodon sequences to recognize and pair with mRNA codons during translation. |
| translation | The process by which mRNA is decoded by ribosomes to synthesize a polypeptide chain. |
| Term | Definition |
|---|---|
| cell differentiation | The process by which cells become specialized through the selective expression of genes for tissue-specific proteins. |
| constitutively expressed | Genes that are continuously transcribed and translated at relatively constant levels. |
| coordinately regulated | The simultaneous regulation of multiple genes as a group, often in response to the same signal or regulatory mechanism. |
| epigenetic changes | Reversible modifications of DNA or histone proteins that affect gene expression without changing the DNA sequence. |
| gene products | The proteins or RNA molecules produced by the expression of genes that determine cellular function and organism phenotype. |
| inducible | Genes that are expressed only in response to specific environmental signals or regulatory molecules. |
| inducible system | A gene regulation system in prokaryotes where genes are turned on in response to the presence of a substrate or signal molecule. |
| operons | In prokaryotes, a cluster of genes under the control of a single regulatory sequence that are transcribed together as one unit. |
| phenotype | The observable physical and biochemical characteristics of an organism, determined by both genetic and environmental factors. |
| regulatory proteins | Proteins that bind to regulatory sequences to control whether genes are transcribed. |
| regulatory sequences | Stretches of DNA that interact with regulatory proteins to control the transcription of genes. |
| repressible system | A gene regulation system in prokaryotes where genes are turned off in response to the presence of a substrate or signal molecule. |
| tissue-specific proteins | Proteins whose expression is limited to particular cell types or tissues, contributing to cell differentiation. |
| transcription | The process by which RNA polymerase synthesizes RNA molecules using a DNA template strand. |
| transcription factors | Proteins that bind to specific DNA sequences (promoters or enhancers) to regulate the initiation of transcription and control gene expression. |
| Term | Definition |
|---|---|
| differential gene expression | The selective expression of different genes in different cells or at different times, resulting in variation in which proteins are produced. |
| enhancer | A DNA sequence that can be located upstream or downstream of a gene and where transcription factors bind to increase the rate of transcription. |
| gene expression | The process by which information from a gene is used to synthesize functional gene products, typically proteins, which can be influenced by environmental conditions. |
| gene regulation | The mechanisms that control when and how often a gene is expressed, determining the amount of gene product produced. |
| negative regulatory molecules | Molecules that inhibit gene expression by binding to DNA and blocking transcription. |
| phenotype | The observable physical and biochemical characteristics of an organism, determined by both genetic and environmental factors. |
| phenotypic differences | Observable variations in the physical or biochemical characteristics of cells or organisms resulting from differences in gene expression and protein production. |
| promoter | A DNA sequence located upstream of a gene where RNA polymerase and transcription factors bind to initiate transcription. |
| RNA polymerase | An enzyme that catalyzes the synthesis of RNA by reading a DNA template strand and linking RNA bases in sequence. |
| small RNA molecules | Short RNA sequences, such as microRNAs, that regulate gene expression by controlling mRNA translation or degradation. |
| transcription | The process by which RNA polymerase synthesizes RNA molecules using a DNA template strand. |
| transcription factors | Proteins that bind to specific DNA sequences (promoters or enhancers) to regulate the initiation of transcription and control gene expression. |
| transcription start site | The location on DNA where RNA polymerase begins synthesizing RNA, relative to which promoter and enhancer sequences are positioned. |
| Term | Definition |
|---|---|
| aneuploidy | An abnormal number of chromosomes resulting from nondisjunction, often causing new phenotypes. |
| beneficial mutation | A mutation that has a positive effect on the organism's phenotype or survival. |
| chromosome structure | The physical organization of chromosomes, including the arrangement and integrity of genetic material; alterations can lead to genetic disorders. |
| conjugation | A process of horizontal gene transfer in prokaryotes involving direct cell-to-cell transfer of DNA. |
| cystic fibrosis | A genetic disorder caused by mutations in the CFTR gene that disrupt ion transport in cells. |
| detrimental mutation | A mutation that has a negative effect on the organism's phenotype or survival. |
| DNA repair mechanisms | Cellular processes that identify and correct errors in DNA to maintain genetic integrity. |
| DNA replication | The process by which DNA makes an exact copy of itself, which can be subject to errors that cause mutations. |
| DNA sequences | The specific order of nucleotide bases (A, T, G, C) in a DNA molecule that encodes genetic information. |
| frameshift mutation | A type of mutation in which one or more nucleotides are inserted or deleted, causing the reading frame of the genetic code to shift. |
| genetic variation | Differences in DNA sequences and alleles that exist within a population. |
| genotype | The genetic makeup of an organism; the specific alleles present for each gene. |
| meiosis | A process of cell division in diploid organisms that produces haploid gamete cells, reducing chromosome number by half for sexual reproduction. |
| mitosis | A process of cell division in eukaryotes that produces two genetically identical daughter cells, each with a complete copy of the parent cell's genome. |
| mutation | An alteration in a DNA sequence that can cause changes in the type or amount of protein produced and the resulting phenotype. |
| mutations | Random changes in DNA sequences that create new genetic variations in populations. |
| natural selection | A major mechanism of evolution in which individuals with more favorable phenotypes are more likely to survive and reproduce, passing advantageous traits to subsequent generations. |
| neutral mutation | A mutation that has no effect on the organism's phenotype or protein function. |
| nondisjunction | The failure of chromosomes to separate properly during mitosis or meiosis, resulting in changes in chromosome number. |
| nonsense mutation | A type of point mutation that results in a premature stop codon, terminating protein synthesis early. |
| phenotype | The observable physical and biochemical characteristics of an organism, determined by both genetic and environmental factors. |
| point mutation | A type of mutation in which one nucleotide is substituted for a different nucleotide in the DNA sequence. |
| prokaryotes | Single-celled organisms without a membrane-bound nucleus, such as bacteria and archaea. |
| reading frame | The grouping of nucleotides into consecutive triplets (codons) that are read during translation to produce a protein. |
| recombination | The process by which genetic material is exchanged between homologous chromosomes, creating new combinations of alleles. |
| reproductive processes | Biological mechanisms that generate genetic variation and are conserved across different organisms. |
| sickle cell anemia | A genetic disorder caused by mutations in hemoglobin genes that result in abnormal red blood cell shape and reduced oxygen transport. |
| silent mutation | A type of mutation in which a change in the nucleotide sequence has no effect on the amino acid sequence or protein produced. |
| transduction | A process of horizontal gene transfer in prokaryotes where viruses transfer genetic information from one cell to another. |
| transformation | A process of horizontal gene transfer in prokaryotes where cells take up DNA from their environment. |
| transposition | The movement of DNA segments (transposons) within or between DNA molecules, creating genetic variation. |
| triploidy | A condition in which an organism has three complete sets of chromosomes instead of the normal two. |
| variation | Differences in traits among individuals within a population due to genetic and environmental factors. |
| Term | Definition |
|---|---|
| bacterial transformation | The process of introducing foreign DNA into bacterial cells, allowing them to take up and express new genetic material. |
| DNA denaturation | The process of separating double-stranded DNA into single strands, typically by heating. |
| DNA fingerprint | A unique pattern of DNA sequences from an individual that allows for comparison and identification of DNA samples. |
| DNA sequencing | Technology that determines the precise order of nucleotides in a DNA molecule. |
| gel electrophoresis | A laboratory process that separates DNA fragments based on their size and electrical charge by moving them through a gel matrix. |
| gene cloning | The process of creating identical copies of a specific DNA fragment for propagation and study. |
| genetic engineering techniques | Methods used to analyze, manipulate, or alter DNA and RNA in organisms. |
| polymerase chain reaction | A technique that amplifies specific DNA fragments through repeated cycles of denaturing, primer annealing, and DNA extension. |
| primer annealing | The binding of short DNA sequences (primers) to complementary regions on a template DNA strand during PCR. |
| transgenic animals | Animals that have been genetically modified to contain foreign DNA from another organism. |
| Term | Definition |
|---|---|
| abiotic environment | The non-living physical and chemical components of an ecosystem, such as temperature, light, and water. |
| biotic environment | The living components of an ecosystem, including organisms and their interactions. |
| competition for limited resources | The struggle among organisms for access to finite environmental resources, which results in differential survival and reproduction. |
| differential survival | The unequal survival rates of individuals in a population based on differences in their traits or phenotypes. |
| evolution | The process of change in living organisms over time, involving genetic modifications and adaptation to environments. |
| evolutionary fitness | The measure of an organism's reproductive success, determined by how many viable offspring it produces. |
| favorable phenotype | A set of observable traits that increases an organism's likelihood of survival and reproduction in its environment. |
| genetic variation | Differences in DNA sequences and alleles that exist within a population. |
| natural selection | A major mechanism of evolution in which individuals with more favorable phenotypes are more likely to survive and reproduce, passing advantageous traits to subsequent generations. |
| offspring | The individual organisms produced by reproduction from parent organisms. |
| phenotype | The observable physical and biochemical characteristics of an organism, determined by both genetic and environmental factors. |
| population | A group of organisms of the same species living in the same geographic area. |
| reproductive success | An organism's ability to produce viable offspring that survive and reproduce. |
| traits | Specific characteristics or features of an organism that can be inherited and passed to offspring. |
| Term | Definition |
|---|---|
| adaptive radiation | The rapid evolution and diversification of a single ancestral species into multiple species that occupy different habitats or ecological niches. |
| allopatric speciation | Speciation that occurs in populations that are geographically isolated from one another. |
| biological species concept | A definition of species based on the ability of organisms to interbreed and produce viable, fertile offspring. |
| convergent evolution | Evolution in which different populations or species develop similar phenotypic adaptations in response to similar selective pressures. |
| divergent evolution | Evolution in which populations or species become increasingly different from each other, often due to adaptation to different habitats. |
| fertile | Capable of producing offspring; able to reproduce. |
| gene flow | The transfer of alleles into or out of a population as a result of migration. |
| geographic isolation | The physical separation of populations by geographic barriers that prevents gene flow between them. |
| gradualism | A pattern of evolution in which evolutionary change occurs slowly and continuously over hundreds of thousands or millions of years. |
| interbreeding | The process of mating and reproduction between members of different populations or groups. |
| phenotypic diversification | An increase in the variety of observable physical traits within or among populations. |
| post-zygotic mechanisms | Reproductive barriers that reduce the viability or fertility of hybrid offspring after zygote formation. |
| pre-zygotic mechanisms | Reproductive barriers that prevent fertilization from occurring by preventing gamete fusion before zygote formation. |
| punctuated equilibrium | A pattern of evolution in which rapid evolutionary change occurs after long periods of stasis, or little change. |
| reproductive isolation | The inability of different populations or species to interbreed and produce viable, fertile offspring. |
| reproductively isolated | A condition in which two populations are unable to interbreed and exchange genetic information, preventing gene flow between them. |
| selective pressure | Environmental factors that influence which traits are advantageous for survival and reproduction in a population. |
| speciation | The evolutionary process by which new species arise from existing species through reproductive isolation and genetic divergence. |
| stasis | A period of little or no evolutionary change in a population or species. |
| sympatric speciation | Speciation that occurs within populations that share the same geographic area or have geographic overlap. |
| viable | Capable of living, developing, or functioning successfully. |
| Term | Definition |
|---|---|
| adaptive alleles | Alleles that increase an organism's fitness and ability to survive and reproduce in a particular environment. |
| allele | Different versions of a gene that can exist at the same location on a chromosome. |
| deleterious alleles | Alleles that decrease an organism's fitness and ability to survive and reproduce in a particular environment. |
| environmental pressure | External environmental conditions or stressors that affect the survival and reproduction of organisms in a population. |
| extinction | The permanent disappearance of a species from Earth, occurring when all individuals of that species die. |
| genetic diversity | The variety of different alleles and genes present within a population or species. |
| population dynamics | Changes in population size and structure over time, influenced by interactions with other populations and environmental factors. |
| resilience | The ability of an ecosystem to withstand and recover from environmental changes or disturbances. |
| selective pressure | Environmental factors that influence which traits are advantageous for survival and reproduction in a population. |
| Term | Definition |
|---|---|
| base-pairing | The complementary bonding between nitrogenous bases in nucleic acids that enables accurate replication and information transfer. |
| fossil evidence | Physical remains or traces of ancient organisms preserved in rock that provide direct evidence of past life on Earth. |
| genetic continuity | The unbroken transmission of genetic information from one generation to the next through accurate replication of genetic material. |
| genetic material | Molecules that store and transmit hereditary information in living organisms. |
| geological evidence | Physical and chemical evidence from Earth's rocks, minerals, and geological structures that provides information about Earth's history and the conditions of early life. |
| RNA replication | The process by which RNA molecules make copies of themselves through base-pairing interactions. |
| RNA world hypothesis | A scientific model proposing that RNA served as the earliest genetic material and catalyst in primitive life forms before the evolution of DNA and proteins. |
| scientific evidence | Data and observations from empirical research that support or refute scientific claims, including evidence for evolution. |
| Term | Definition |
|---|---|
| fitness | An organism's ability to survive and reproduce successfully, passing its genes to the next generation. |
| molecules | Chemical compounds made up of atoms that perform specific functions within cells. |
| natural selection | A major mechanism of evolution in which individuals with more favorable phenotypes are more likely to survive and reproduce, passing advantageous traits to subsequent generations. |
| phenotypic variation | Differences in observable characteristics or traits among individuals in a population. |
| population | A group of organisms of the same species living in the same geographic area. |
| selective pressure | Environmental factors that influence which traits are advantageous for survival and reproduction in a population. |
| variation | Differences in traits among individuals within a population due to genetic and environmental factors. |
| Term | Definition |
|---|---|
| artificial selection | The process by which humans deliberately choose organisms with specific traits to breed together, thereby changing the frequency of traits in a population over time. |
| diversity | The variety of different traits, alleles, and genetic variation present within a population. |
| variation | Differences in traits among individuals within a population due to genetic and environmental factors. |
| Term | Definition |
|---|---|
| allele frequencies | The proportion or percentage of a specific allele in a population's gene pool. |
| bottleneck effect | A type of genetic drift that occurs when a population is drastically reduced in size, causing random changes in allele frequencies. |
| evolution | The process of change in living organisms over time, involving genetic modifications and adaptation to environments. |
| founder effect | A type of genetic drift that occurs when a small group of individuals establishes a new population, resulting in allele frequencies that differ from the original population. |
| gene flow | The transfer of alleles into or out of a population as a result of migration. |
| genetic drift | Random changes in allele frequencies in a population due to nonselective processes, particularly in small populations. |
| genetic makeup | The complete set of alleles and genes present in a population that determine the heritable traits of its members. |
| genetic variation | Differences in DNA sequences and alleles that exist within a population. |
| migration | The movement of individuals (and their alleles) into or out of a population; must be absent for Hardy-Weinberg Equilibrium. |
| mutation | An alteration in a DNA sequence that can cause changes in the type or amount of protein produced and the resulting phenotype. |
| mutations | Random changes in DNA sequences that create new genetic variations in populations. |
| random occurrences | Unpredictable events that affect allele frequencies in populations independent of natural selection. |
| random processes | Unpredictable events that cause changes in allele frequencies in populations, independent of natural selection. |
| Term | Definition |
|---|---|
| allele frequencies | The proportion or percentage of a specific allele in a population's gene pool. |
| genotype frequencies | The proportion or percentage of each genotype combination in a population. |
| Hardy-Weinberg Equilibrium | A model describing a non-evolving population where allele and genotype frequencies remain constant across generations. |
| large population size | A condition for Hardy-Weinberg Equilibrium where a population is large enough to prevent random changes in allele frequencies due to chance events. |
| migration | The movement of individuals (and their alleles) into or out of a population; must be absent for Hardy-Weinberg Equilibrium. |
| mutations | Random changes in DNA sequences that create new genetic variations in populations. |
| natural selection | A major mechanism of evolution in which individuals with more favorable phenotypes are more likely to survive and reproduce, passing advantageous traits to subsequent generations. |
| non-evolving population | A population in which allele frequencies do not change over time because evolutionary forces are absent. |
| null hypothesis | A baseline model used for comparison; in this context, Hardy-Weinberg Equilibrium serves as a reference point to detect when populations are evolving. |
| random mating | A condition where individuals in a population mate without preference for specific genotypes; required for Hardy-Weinberg Equilibrium. |
| Term | Definition |
|---|---|
| biochemical data | Information about molecular and chemical composition of organisms, such as DNA and proteins, that provides evidence for evolution. |
| carbon-14 dating | A radiometric dating method that measures the decay of the carbon-14 isotope to determine the age of fossils. |
| common ancestry | The concept that all organisms share a common evolutionary origin and are related through descent from earlier ancestral species. |
| DNA nucleotide sequences | The specific order of nucleotides in DNA that can be compared between organisms to determine evolutionary relationships. |
| evolution | The process of change in living organisms over time, involving genetic modifications and adaptation to environments. |
| extant organisms | Living organisms that exist in the present day. |
| extinct organisms | Organisms that no longer exist and are known only through fossil records. |
| fossil | Preserved remains or traces of organisms from past geological time periods. |
| geographical data | Information about the distribution and location of organisms across different regions that provides evidence for evolution. |
| geological data | Information about rock layers and Earth's history used to date fossils and understand evolutionary timescales. |
| isotope decay | The process by which unstable isotopes break down over time at a predictable rate, used to determine the age of rocks and fossils. |
| mathematical data | Quantitative analysis and statistical information used to model and support evolutionary patterns and relationships. |
| molecular evidence | Data from DNA nucleotide sequences and protein amino acid sequences that demonstrates evolutionary relationships between organisms. |
| morphological homologies | Structural similarities in different organisms that indicate common ancestry and evolutionary relationships. |
| morphological traits | Physical characteristics or structures of organisms used to determine evolutionary relationships. |
| physical data | Observable structural and anatomical information about organisms that provides evidence for evolution. |
| protein amino acid sequences | The specific order of amino acids in proteins that can be compared between organisms to provide evidence for evolution. |
| scientific evidence | Data and observations from empirical research that support or refute scientific claims, including evidence for evolution. |
| vestigial structures | Reduced or non-functional body parts that are remnants from ancestral organisms and provide evidence of common ancestry. |
| Term | Definition |
|---|---|
| common ancestry | The concept that all organisms share a common evolutionary origin and are related through descent from earlier ancestral species. |
| eukaryotes | Organisms whose cells contain a membrane-bound nucleus and other membrane-bound organelles. |
| functional evidence | Observable processes and biochemical functions of cells and organisms that indicate evolutionary relationships and common ancestry. |
| intron | A non-coding segment of a eukaryotic gene that is removed from the mRNA transcript during RNA processing. |
| linear chromosomes | Chromosomes with defined endpoints found in eukaryotic cell nuclei, as opposed to the circular chromosomes found in prokaryotes. |
| membrane-bound organelle | Specialized structures within eukaryotic cells enclosed by a membrane that perform specific cellular functions. |
| structural evidence | Physical characteristics of cells and organisms that indicate evolutionary relationships and common ancestry. |
| Term | Definition |
|---|---|
| antibiotic resistance | The ability of bacteria and other microorganisms to survive and reproduce in the presence of antibiotics that would normally kill them. |
| chemotherapy drug resistance | The ability of cancer cells to survive and proliferate despite exposure to chemotherapy drugs. |
| emergent diseases | Infectious diseases that have recently appeared in a population or are rapidly increasing in incidence or geographic range. |
| evolution | The process of change in living organisms over time, involving genetic modifications and adaptation to environments. |
| fossil record | The preserved remains and traces of organisms from past geological periods that document changes in life forms over time. |
| genomic changes | Alterations in the DNA sequence of an organism's genome that accumulate over time. |
| herbicide resistance | The ability of plants to survive and grow in the presence of herbicides designed to kill them. |
| pathogens | Organisms or agents, such as bacteria, viruses, or parasites, that cause disease in host organisms. |
| pesticide resistance | The ability of organisms, particularly insects and plants, to survive exposure to pesticides that would normally be lethal. |
| Term | Definition |
|---|---|
| cladogram | A branching diagram that shows hypothetical evolutionary relationships among lineages without indicating time scale or the amount of evolutionary change between groups. |
| DNA sequence similarities | Resemblances in the order of nucleotides in DNA between different organisms, used to infer evolutionary relationships. |
| evolutionary relationship | A connection between organisms based on their shared ancestry and descent from a common ancestor. |
| molecular clock | A method that uses the rate of molecular change (mutations) to estimate the time since organisms diverged from a common ancestor. |
| molecular evidence | Data from DNA nucleotide sequences and protein amino acid sequences that demonstrates evolutionary relationships between organisms. |
| morphological similarities | Structural and physical resemblances between organisms based on body form and anatomy. |
| morphological traits | Physical characteristics or structures of organisms used to determine evolutionary relationships. |
| most recent common ancestor | The most immediate ancestral species or population from which two or more groups diverged during evolution. |
| nodes | Points on a phylogenetic tree or cladogram that represent the most recent common ancestor of two or more groups or lineages. |
| out-group | The lineage in a phylogenetic tree or cladogram that is least closely related to the remainder of the organisms being compared. |
| phylogenetic tree | A diagram that shows hypothetical evolutionary relationships among lineages, including time scale and the amount of evolutionary change over time. |
| protein sequence similarities | Resemblances in the order of amino acids in proteins between different organisms, used to infer evolutionary relationships. |
| shared derived characters | Traits that are present in multiple lineages and were inherited from a common ancestor, indicating common ancestry and used to construct phylogenetic trees and cladograms. |
| speciation | The evolutionary process by which new species arise from existing species through reproductive isolation and genetic divergence. |
| Term | Definition |
|---|---|
| audible signals | Communication through sound that can be perceived by hearing. |
| behavioral response | A change in an organism's actions or conduct in reaction to changes in its internal or external environment. |
| bird songs | Vocalizations produced by birds used for communication, territorial defense, and mate attraction. |
| chemical signals | Communication through chemical substances that can be perceived by smell or taste. |
| colony behavior | Coordinated behavior of insects living together in organized groups with specialized roles. |
| cooperative behavior | Behavior in which organisms work together in ways that benefit the group and may increase individual fitness. |
| differential reproductive success | Variation in the number of offspring produced by different individuals, leading to differences in genetic contribution to future generations. |
| diurnal activity | Behavioral pattern in which an organism is active primarily during daytime hours. |
| dominance | A behavioral or social status indicating an organism's rank or authority within a group. |
| electrical signals | Communication through electrical impulses that can be perceived by specialized receptors. |
| fight-or-flight response | A physiological response that prepares an organism to either confront or escape from a perceived threat. |
| fitness | An organism's ability to survive and reproduce successfully, passing its genes to the next generation. |
| flock behavior | Coordinated movement and action of a group of birds flying together. |
| herd behavior | Coordinated movement and action of a group of animals of the same species. |
| innate behaviors | Behaviors that are genetically determined and performed without prior learning or experience. |
| kin selection | The process by which organisms increase their fitness by helping relatives survive and reproduce, even at a cost to themselves. |
| kinesis | A non-directional movement response of an organism that changes in rate based on stimulus intensity. |
| learned behaviors | Behaviors that are acquired through experience, observation, or training rather than being genetically determined. |
| natural selection | A major mechanism of evolution in which individuals with more favorable phenotypes are more likely to survive and reproduce, passing advantageous traits to subsequent generations. |
| nocturnal activity | Behavioral pattern in which an organism is active primarily during nighttime hours. |
| pack behavior | Coordinated behavior of animals living and hunting together as a group. |
| parent and offspring interactions | Behaviors and communication between parents and their young that affect survival and development. |
| photoperiodism | A physiological response in plants to changes in the length of day and night, affecting processes like flowering and dormancy. |
| phototropism | A directional growth response in plants toward or away from a light source. |
| physiological response | A change in an organism's internal body functions or processes in reaction to changes in its internal or external environment. |
| plant responses to herbivory | Behavioral or physiological mechanisms by which plants respond to damage or feeding by herbivorous organisms. |
| population | A group of organisms of the same species living in the same geographic area. |
| predator warning | A behavioral or physiological response in which an organism communicates the presence of danger to other organisms. |
| predatory warnings | Signals or behaviors used by organisms to alert others to the presence of a predator. |
| reproductive success | An organism's ability to produce viable offspring that survive and reproduce. |
| schooling behavior | Coordinated movement and action of a group of fish swimming together. |
| signaling behaviors | Behaviors that organisms use to communicate information to other organisms through various mechanisms. |
| swarming behavior | Coordinated movement of a large group of insects or animals moving together. |
| tactile signals | Communication through touch that can be perceived by physical contact. |
| taxis | A directed movement response of an organism toward or away from a stimulus. |
| territorial marking | Behavior in which organisms use signals or physical marks to indicate and defend their territory. |
| territory | An area defended by an organism or group of organisms against others of the same or different species. |
| visual signals | Communication through light, color, or movement that can be perceived by sight. |
| Term | Definition |
|---|---|
| abiotic reservoirs | Non-living components of ecosystems that store matter, such as atmosphere, soil, and water. |
| ammonification | The process by which decomposers break down organic nitrogen compounds into ammonia. |
| asexual reproduction | Reproduction that produces offspring genetically identical to the parent without the fusion of gametes. |
| assimilation | The process by which organisms take up and incorporate nutrients into their biological molecules. |
| autotrophs | Organisms that capture energy from physical or chemical sources in the environment and convert it into organic compounds to fuel their own growth and metabolism. |
| biogeochemical cycles | Cycles that move matter and nutrients between biotic and abiotic reservoirs in ecosystems. |
| biomass | The total mass of living organisms in a population or trophic level. |
| biomes | Large geographic areas with similar climate, vegetation, and animal life. |
| biotic reservoirs | Living organisms and organic matter that store matter within ecosystems. |
| carbon cycle | The cycle involving the movement of carbon atoms through the biosphere, atmosphere, and organisms. |
| carnivores | Heterotrophs that obtain energy by consuming other animals. |
| cellular respiration | The metabolic process by which cells break down biological macromolecules to release energy and synthesize ATP. |
| chemosynthetic organisms | Autotrophs that capture energy from inorganic chemical compounds in their environment, independent of sunlight. |
| combustion | The burning of organic matter or fossil fuels, which releases carbon dioxide into the atmosphere. |
| community | A group of interacting populations of different species that live in the same area and change over time based on interactions between those populations. |
| condensation | The process by which water vapor cools and changes into liquid form in the atmosphere. |
| conservation of matter | The principle that matter is neither created nor destroyed but is recycled through biogeochemical cycles. |
| decomposer | Organisms, such as bacteria and fungi, that break down dead organic matter and return nutrients to the ecosystem. |
| decomposition | The process by which decomposers break down dead organic matter, releasing carbon dioxide and nutrients. |
| denitrification | The process by which soil microorganisms convert nitrate back into nitrogen gas, returning it to the atmosphere. |
| ecosystem | A community of living organisms interacting with each other and their physical environment. |
| ecosystem disruption | A disturbance to the normal functioning and balance of an ecosystem caused by changes in environmental factors. |
| ectotherms | Organisms that lack efficient internal mechanisms for regulating body temperature and rely on behavioral or environmental factors to regulate their temperature. |
| endotherms | Organisms that use thermal energy generated by their own metabolism to maintain a relatively constant body temperature. |
| energy availability | The amount of energy accessible to organisms in an ecosystem, which can change based on factors like sunlight or food resources. |
| energy flow | The movement of energy through an ecosystem from the sun through producers and consumers to decomposers. |
| energy storage | The accumulation of energy in an organism, resulting from a net gain of energy that can be used for growth and reproduction. |
| evaporation | The process by which water changes from liquid to gas and enters the atmosphere. |
| food chain | A linear sequence showing the transfer of energy from one organism to the next through feeding relationships. |
| food web | A network of interconnected food chains showing multiple feeding relationships in an ecosystem. |
| herbivores | Heterotrophs that obtain energy by consuming plants and other autotrophs. |
| heterotrophs | Organisms that obtain energy by consuming organic matter derived from autotrophs or other organisms. |
| homeostasis | The maintenance of stable internal environmental conditions in an organism despite external and internal changes. |
| hydrologic cycle | The cycle involving water movement and storage through evaporation, condensation, precipitation, and transpiration. |
| matter cycles | The movement and recycling of chemical elements and compounds between organisms and the physical environment. |
| metabolism | The sum of all chemical reactions in an organism that produce energy and build or break down molecules. |
| nitrification | The process by which soil microorganisms convert ammonia into nitrite and nitrate. |
| nitrogen cycle | The cycle involving the movement of nitrogen between the atmosphere, soil, and organisms through various microbial processes. |
| nitrogen fixation | The process by which nitrogen gas from the atmosphere is converted into ammonia by microorganisms. |
| omnivores | Heterotrophs that obtain energy by consuming both plants and animals. |
| phosphorus cycle | The cycle involving the movement of phosphorus through soil, organisms, and water in ecosystems. |
| photosynthesis | The series of reactions that use carbon dioxide, water, and light energy to produce carbohydrates and oxygen, allowing organisms to capture and store energy from the sun. |
| photosynthetic organisms | Autotrophs that capture energy from sunlight and convert it into chemical energy stored in organic compounds. |
| population | A group of organisms of the same species living in the same geographic area. |
| population size | The total number of individual organisms of the same species in a population at a given time. |
| precipitation | Water falling from clouds to Earth's surface as rain, snow, sleet, or hail. |
| primary consumer | An organism that feeds directly on producers; a herbivore. |
| primary productivity | The rate at which photosynthetic organisms capture solar energy and convert it into organic matter in an ecosystem. |
| producer | Organisms, primarily plants and photosynthetic organisms, that convert light energy into chemical energy through photosynthesis. |
| quaternary consumer | An organism that feeds on tertiary consumers; a carnivore at the fourth trophic level. |
| reproductive diapause | A period of suspended or delayed reproduction in response to unfavorable environmental conditions or limited energy availability. |
| reproductive strategies | Different approaches organisms use to reproduce in response to environmental conditions and energy availability. |
| scavengers | Heterotrophs that obtain energy by consuming dead organisms or organic waste. |
| secondary consumer | An organism that feeds on primary consumers; a carnivore or omnivore at the second trophic level. |
| sexual reproduction | Reproduction involving the fusion of gametes from two parents, producing genetically diverse offspring. |
| tertiary consumer | An organism that feeds on secondary consumers; a carnivore at the third trophic level. |
| transpiration | The process by which water is released from plants into the atmosphere. |
| trophic level | A position in a food chain or food web occupied by organisms that obtain energy in the same way, including producers, consumers, and decomposers. |
| trophic pyramid | A diagram representing the relative amounts of energy or biomass at each trophic level in an ecosystem. |
| weathering | The process by which rocks break down, releasing minerals such as phosphate into soil and water. |
| Term | Definition |
|---|---|
| adaptation | A genetic variation that is favored by natural selection and manifests as a trait providing an advantage to an organism in a particular environment. |
| birth rate | The number of new individuals produced per unit time in a population. |
| death rate | The number of individuals that die per unit time in a population. |
| exponential growth | Population growth that occurs without limiting constraints, resulting in a population that increases at an accelerating rate over time. |
| per capita growth rate | The rate at which a population grows per individual organism in the population. |
| population growth dynamics | The changes in population size over time, determined by the rates at which individuals are born and die. |
| population size | The total number of individual organisms of the same species in a population at a given time. |
| Term | Definition |
|---|---|
| carrying capacity | The maximum population size of a species that an ecosystem can sustain indefinitely based on available resources. |
| density-dependent factors | Limiting factors whose effects on population growth increase as population density increases, such as disease, competition, and predation. |
| density-independent factors | Limiting factors that affect population growth regardless of population density, such as weather, natural disasters, and seasonal changes. |
| logistic growth model | A model of population growth that accounts for limited resources, showing how population growth slows as it approaches carrying capacity. |
| resource availability | The quantity and accessibility of resources in an environment that support population growth and survival. |
| Term | Definition |
|---|---|
| commensalism | A symbiotic relationship where one organism benefits while the other organism is neither helped nor harmed. |
| community | A group of interacting populations of different species that live in the same area and change over time based on interactions between those populations. |
| community structure | The composition and organization of a community, determined by the types and relative abundances of populations and their interactions. |
| competition | An interaction between populations where organisms compete for the same limited resources, negatively affecting both populations. |
| mutualism | A symbiotic relationship where both organisms benefit from the interaction. |
| niche partitioning | The division of resources among species that allows multiple populations to coexist by utilizing different aspects of their environment. |
| parasitism | A symbiotic relationship where one organism (parasite) benefits while the other organism (host) is harmed. |
| population | A group of organisms of the same species living in the same geographic area. |
| population dynamics | Changes in population size and structure over time, influenced by interactions with other populations and environmental factors. |
| predation | An interaction where one organism (predator) hunts and consumes another organism (prey). |
| predator/prey interactions | Relationships between populations where one organism (predator) hunts and consumes another (prey), influencing population dynamics and energy flow. |
| Simpson's Diversity Index | A quantitative measure of species diversity that accounts for both the number of species and the evenness of their abundance in a community. |
| species composition | The identity and relative abundance of different species present in a community. |
| species diversity | A measure of the variety of species in a community, accounting for both the number of species and their relative abundance. |
| symbiosis | A close, long-term relationship between two different species living together. |
| trophic cascades | Ecological changes triggered by the addition or removal of top predators, affecting multiple levels of the food chain. |
| Term | Definition |
|---|---|
| abiotic factors | Non-living physical and chemical components of an ecosystem, such as temperature, light, water, and soil. |
| biotic factors | Living organisms and biological components of an ecosystem, including animals, plants, fungi, and microorganisms. |
| ecosystem | A community of living organisms interacting with each other and their physical environment. |
| ecosystem collapse | The sudden loss of ecosystem structure and function, often resulting from the removal of a keystone species. |
| ecosystem diversity | The variety of different ecosystems and the range of species and ecological processes within them. |
| keystone species | A species whose presence or absence has a disproportionate effect on the structure and function of an ecosystem relative to its abundance. |
| producer | Organisms, primarily plants and photosynthetic organisms, that convert light energy into chemical energy through photosynthesis. |
| resilience | The ability of an ecosystem to withstand and recover from environmental changes or disturbances. |
| Term | Definition |
|---|---|
| adaptation | A genetic variation that is favored by natural selection and manifests as a trait providing an advantage to an organism in a particular environment. |
| biogeographical studies | Scientific research that examines the distribution of organisms and ecosystems across different geographic regions and how they change over time. |
| biomagnification | The process by which the concentration of a substance, such as a toxin or pollutant, increases in organisms at higher trophic levels in a food chain. |
| competitors | Organisms that vie for the same resources, such as food, water, or space. |
| continental drift | The movement of Earth's continents over geological time, which alters the distribution of habitats and ecosystems. |
| ecosystem distribution | The geographic locations and patterns where different ecosystems are found across the biosphere. |
| ecosystem dynamics | The interactions and changes that occur within an ecosystem, including relationships between species and how populations respond to environmental changes. |
| ecosystem structure | The physical organization and composition of an ecosystem, including the arrangement of organisms, habitats, and abiotic factors. |
| El Niño | A meteorological phenomenon characterized by warming of ocean temperatures in the Pacific, causing significant changes in global weather patterns and ecosystems. |
| environmental pressure | External environmental conditions or stressors that affect the survival and reproduction of organisms in a population. |
| eutrophication | The process by which excessive nutrients, particularly nitrogen and phosphorus, accumulate in a water body, leading to excessive algal growth and oxygen depletion. |
| extinction | The permanent disappearance of a species from Earth, occurring when all individuals of that species die. |
| genetic variation | Differences in DNA sequences and alleles that exist within a population. |
| geological activity | Physical processes and events related to Earth's structure and composition, such as volcanic eruptions, earthquakes, and continental drift, that can alter ecosystems. |
| global climate change | Long-term shifts in Earth's climate patterns and average temperatures that affect ecosystems worldwide. |
| habitat change | Alterations in the physical and biological conditions of a habitat that affect the organisms living there. |
| heterozygote advantage | A situation where the heterozygous genotype has higher relative fitness than either homozygous genotype. |
| heterozygous genotype | A genotype with two different alleles for a particular gene. |
| homozygous dominant genotype | A genotype with two copies of the dominant allele for a particular gene. |
| homozygous recessive genotype | A genotype with two copies of the recessive allele for a particular gene. |
| invasive species | A species that is introduced to a new environment, either intentionally or unintentionally, and can exploit available niches or outcompete native species for resources. |
| meteorological activity | Atmospheric and weather-related phenomena, such as storms, precipitation patterns, and climate events, that influence ecosystem conditions. |
| mutations | Random changes in DNA sequences that create new genetic variations in populations. |
| native species | Species that naturally occur and belong in a particular ecosystem. |
| niche | The specific role and position a species has in its environment, including the resources it uses and the conditions it requires to survive. |
| outcompete | To surpass other organisms in competition for limited resources, often resulting in reduced survival or reproduction of the competing species. |
| predators | Organisms that hunt and consume other organisms for food. |
| relative fitness | The measure of an organism's reproductive success compared to other individuals in the population. |
| selection | The process by which certain traits become more or less common in a population based on their effect on survival and reproduction. |
| trait | A characteristic or feature of an organism that is determined by its genes and expressed in its phenotype. |
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