Biology for Non-STEM Majors Unit 2 Review: Chemistry of Life

What's This Unit All About?

• Explores the fundamental chemical principles underlying biological processes
• Investigates the structure and function of key molecules essential for life (proteins, carbohydrates, lipids, nucleic acids)
• Examines the role of water in biological systems as a universal solvent
• Introduces the concept of pH and its significance in maintaining homeostasis
  • Discusses buffers and their role in regulating pH in living organisms
• Delves into the nature of chemical bonds and their importance in forming complex biological molecules
• Covers the basics of atomic structure and how it relates to the properties of elements
• Highlights the significance of enzymes in catalyzing chemical reactions in living systems
• Connects the principles of chemistry to everyday life, demonstrating their relevance in various aspects of biology (nutrition, medicine, environmental science)

Key Molecules of Life

• Proteins: Essential macromolecules involved in various biological processes (enzymes, structural components, hormones)
  • Composed of amino acids linked together by peptide bonds
  • Primary, secondary, tertiary, and quaternary structures determine protein function
• Carbohydrates: Primary energy source for living organisms and structural components in cell walls (plants) and exoskeletons (insects)
  • Classified as monosaccharides (glucose), disaccharides (sucrose), and polysaccharides (starch, cellulose)
• Lipids: Diverse group of hydrophobic molecules with various functions (energy storage, cell membrane components, hormones)
  • Include fats, oils, waxes, and steroids
  • Triglycerides are the most common type of lipid, consisting of glycerol and three fatty acids
• Nucleic acids: Store and transmit genetic information in living organisms
  • Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA)
  • Composed of nucleotides, each containing a sugar, phosphate group, and nitrogenous base
• Vitamins and minerals: Essential micronutrients required for proper functioning of biological processes
  • Vitamins are organic compounds (vitamin C, B-complex vitamins)
  • Minerals are inorganic elements (iron, calcium, potassium)

Atoms and Chemical Bonds

• Atoms: Building blocks of matter, consisting of protons, neutrons, and electrons
  • Protons and neutrons form the nucleus, while electrons orbit in shells
  • Atomic number represents the number of protons, determining the element's identity
• Chemical bonds: Interactions between atoms that hold molecules together
  • Ionic bonds: Electrostatic attraction between oppositely charged ions (sodium chloride)
  • Covalent bonds: Sharing of electrons between atoms (water, carbon dioxide)
    • Single, double, and triple covalent bonds, depending on the number of shared electron pairs
  • Hydrogen bonds: Weak electrostatic attraction between hydrogen and electronegative atoms (oxygen, nitrogen)
    • Crucial for maintaining the structure of proteins and DNA
• Electronegativity: Ability of an atom to attract electrons in a chemical bond
  • Influences the polarity of molecules and their interactions with other molecules
• Valence electrons: Electrons in the outermost shell of an atom, involved in chemical bonding
  • Atoms tend to achieve a stable octet configuration through bonding

Water: The Universal Solvent

• Water: Essential for life, with unique properties that make it a universal solvent
  • Polar molecule due to the uneven distribution of charge between oxygen and hydrogen atoms
  • Forms hydrogen bonds with other water molecules and polar substances
• Hydrophilic substances: Molecules that readily dissolve in water (sugars, salts)
  • Attracted to water due to their polarity or ability to form hydrogen bonds
• Hydrophobic substances: Molecules that do not readily dissolve in water (lipids, oils)
  • Lack polar groups or charge, making them unable to form strong interactions with water
• Cohesion: Attraction between water molecules, resulting in high surface tension
  • Allows water to move through narrow spaces (xylem in plants) and form droplets
• Adhesion: Attraction between water molecules and other surfaces
  • Enables capillary action, allowing water to move up through narrow tubes against gravity
• High specific heat capacity: Water requires a large amount of energy to change its temperature
  • Helps regulate temperature in living organisms and maintains stable aquatic environments

pH and Buffers

• pH: Measure of the concentration of hydrogen ions (H+) in a solution
  • Ranges from 0 (highly acidic) to 14 (highly basic), with 7 being neutral
  • Logarithmic scale, where each unit change represents a tenfold difference in H+ concentration
• Acids: Substances that donate hydrogen ions (H+) when dissolved in water
  • Examples include hydrochloric acid (HCl), acetic acid (vinegar), and citric acid (lemons)
• Bases: Substances that accept hydrogen ions (H+) when dissolved in water
  • Examples include sodium hydroxide (NaOH), ammonia (NH3), and baking soda (NaHCO3)
• Buffers: Solutions that resist changes in pH when small amounts of acid or base are added
  • Consist of a weak acid and its conjugate base, or a weak base and its conjugate acid
  • Maintain relatively stable pH levels in biological systems (blood, cytoplasm)
• Importance of pH in living systems:
  • Enzymes function optimally within specific pH ranges
  • Proper pH is crucial for maintaining protein structure and function
  • Changes in pH can denature proteins and disrupt cellular processes

Organic Compounds in Living Things

• Organic compounds: Molecules containing carbon, typically found in living organisms
  • Characterized by the presence of carbon-hydrogen bonds
  • Include proteins, carbohydrates, lipids, and nucleic acids
• Monomers: Smaller subunits that can be combined to form larger molecules (polymers)
  • Examples include amino acids (proteins), monosaccharides (carbohydrates), and nucleotides (nucleic acids)
• Polymers: Large molecules composed of repeating monomer subunits
  • Formed through dehydration synthesis, which removes a water molecule between monomers
  • Broken down through hydrolysis, which adds a water molecule to break the bond between monomers
• Isomers: Compounds with the same molecular formula but different arrangements of atoms
  • Structural isomers have different bonding patterns (glucose and fructose)
  • Stereoisomers have the same bonding pattern but different spatial arrangements (cis and trans fats)
• Functional groups: Specific groups of atoms within a molecule that give it distinct chemical properties
  • Examples include hydroxyl (-OH), carboxyl (-COOH), amino (-NH2), and phosphate (-PO4) groups
  • Determine the reactivity and interactions of organic molecules

Enzymes and Chemical Reactions

• Enzymes: Biological catalysts that speed up chemical reactions without being consumed
  • Typically proteins with specific three-dimensional structures
  • Lower the activation energy required for a reaction to occur
• Active site: Region of an enzyme where the substrate binds and the reaction takes place
  • Substrate specificity: Enzymes are specific to their substrates due to the unique shape of the active site
• Cofactors: Non-protein molecules that assist enzymes in their function
  • Can be inorganic (metal ions) or organic (coenzymes)
  • Examples include iron in hemoglobin and vitamin B12 in methylmalonyl-CoA mutase
• Factors affecting enzyme activity:
  • Temperature: Enzymes have an optimal temperature range; extreme temperatures can denature the protein
  • pH: Enzymes function best within a specific pH range; changes in pH can alter the active site's shape
  • Substrate concentration: Increasing substrate concentration increases reaction rate until enzyme saturation
• Enzyme inhibition: Substances that reduce or block enzyme activity
  • Competitive inhibitors: Molecules that resemble the substrate and compete for the active site
  • Non-competitive inhibitors: Molecules that bind to the enzyme at a site other than the active site, altering its shape

Connecting Chemistry to Everyday Life

• Nutrition: Understanding the chemical composition of food and its role in health
  • Macronutrients (proteins, carbohydrates, lipids) and micronutrients (vitamins, minerals)
  • Balanced diet and the importance of essential nutrients
• Medicine: Applying chemical principles to the development and use of drugs
  • Drug design: Creating molecules that interact with specific biological targets (enzymes, receptors)
  • Pharmacokinetics: Studying the absorption, distribution, metabolism, and excretion of drugs in the body
• Environmental science: Investigating the chemical processes in ecosystems and their impact on living organisms
  • Biogeochemical cycles (carbon, nitrogen, phosphorus) and their role in nutrient cycling
  • Pollution and its effects on the environment and human health (acid rain, greenhouse gases, heavy metals)
• Biotechnology: Using living systems and organisms to develop products and processes
  • Genetic engineering: Modifying the genetic material of organisms to produce desired traits (pest-resistant crops, insulin-producing bacteria)
  • Bioremediation: Using microorganisms to break down and remove pollutants from the environment (oil spills, industrial waste)
• Forensic science: Applying chemical techniques to investigate crimes and gather evidence
  • DNA analysis: Using the chemical structure of DNA to identify individuals or establish familial relationships
  • Toxicology: Detecting and identifying toxic substances in biological samples (drugs, poisons)