| 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. |