## AP Biology 1 Final Review Notes This document provides a comprehensive review of key concepts for your AP Biology 1 final exam. We'll cover a wide range of topics, from the properties of water to the structure and function of biological macromolecules. ### I. Properties of Water Water's unique properties are crucial for life. Let's explore why: * **Hydrophobicity of Oil:** Oil is hydrophobic because it's a nonpolar molecule, unlike polar water. Water molecules are strongly attracted to each other (cohesion) due to their polarity, leaving no room for nonpolar oil molecules. Think of it like trying to mix oil and vinegar – they don't blend because of their differing polarities. * **Polarity of Water:** Water's polarity stems from the unequal sharing of electrons between oxygen and hydrogen atoms. Oxygen is more electronegative, creating a slightly negative charge (δ-) near the oxygen and slightly positive charges (δ+) near the hydrogens. This creates a dipole moment. The polarity of water allows it to act as a solvent for many ionic and polar substances. * **Water as a Solvent:** Water's polarity allows it to dissolve many substances, especially ionic compounds and polar molecules. The slightly positive hydrogens attract anions, and the slightly negative oxygen attracts cations. Remember that "like dissolves like." * **Dissolving Salt in Water:** When salt (NaCl) dissolves in water, the polar water molecules surround the Na+ and Cl- ions, separating them and keeping them in solution. This is called hydration. * **Water-Sugar Solution:** Sugar (C₆H₁₂O₆) dissolves in water because both are polar molecules. The slightly positive and negative regions of both molecules attract each other, leading to dissolution. * **Examples of Solutions:** * Sugar + water * Salt + water * Ocean water * **Ice and Life Preservation:** Ice floats because it's less dense than liquid water due to its crystalline structure. This insulates aquatic life during freezing temperatures, preventing bodies of water from freezing solid. This is crucial for the survival of many aquatic organisms. * **Density of Water:** Water's density is unusual; it's most dense at 4°C. This has significant implications for aquatic ecosystems. * **Heat of Vaporization:** The amount of heat required to convert a liquid to a gas. Water has a high heat of vaporization, meaning it takes a lot of energy to evaporate. This helps regulate temperature. * **Specific Heat:** The amount of heat required to raise the temperature of 1 gram of a substance by 1°C. Water has a high specific heat, meaning it resists temperature changes. * **Calorie:** The amount of heat required to raise the temperature of 1 gram of water by 1°C. * **Kilocalorie:** The amount of heat required to raise the temperature of 1000 grams (1 kg) of water by 1°C. * **Temperature:** A measure of the average kinetic energy of the molecules in a substance. * **Adhesion:** Water molecules cling to other surfaces. * **Cohesion:** Water molecules cling to each other. * **Dynamic Equilibrium:** A state where the rate of the forward reaction equals the rate of the reverse reaction. There's no net change in concentration. ### II. Chemical Bonding and Reactions Understanding chemical bonds is fundamental to biology. * **Chemical Reactions:** Involve the rearrangement of atoms and the breaking and forming of chemical bonds. Matter is conserved. * **Endorphins:** Proteins produced by the pituitary gland that act as natural painkillers. * **Opiates:** Drugs derived from the opium poppy that affect mood and behavior. * **Importance of Molecular Shape:** A molecule's shape determines its function. Slight changes in shape can drastically alter a molecule's activity. * **Van der Waals Interactions:** Weak attractions between molecules due to temporary fluctuations in electron distribution. They are individually weak but collectively significant. * **Hydrogen Bonds:** Relatively weak bonds between a hydrogen atom and a highly electronegative atom (like oxygen or nitrogen). Crucial for many biological structures. * **Importance of Weak Bonds:** Weak bonds allow macromolecules to fold into specific shapes and interact reversibly. * **Ionic Bonds:** Bonds formed by the electrostatic attraction between oppositely charged ions. They are weaker in aqueous solutions. * **Cations and Anions:** Cations are positively charged ions, and anions are negatively charged ions. * **Covalent Bonds:** Bonds formed by the sharing of electrons between atoms. Stronger than ionic bonds. * **Electronegativity:** The ability of an atom to attract electrons in a covalent bond. * **Compounds:** Substances composed of two or more elements chemically bonded together. * **Molecules:** Two or more atoms bonded together. * **Unreactive Atoms:** Atoms with a full valence shell of electrons. * **Valence Shell:** The outermost electron shell of an atom. * **Valence Electrons:** Electrons in the valence shell. * **Atomic Structure:** Atoms consist of protons (+), neutrons (neutral), and electrons (-). * **Kinetic Energy:** Energy of motion. * **Potential Energy:** Stored energy. * **Energy:** The capacity to do work. * **Radioactive Isotopes:** Isotopes that emit radiation. Used in research and medicine. * **Isotopes:** Atoms of the same element with different numbers of neutrons. * **Atomic Number:** The number of protons in an atom's nucleus. * **Mass Number:** The total number of protons and neutrons in an atom's nucleus. * **Dalton:** A unit of mass used for atoms and molecules. ### III. Biological Macromolecules Let's delve into the four major classes of biological macromolecules. * **Essential Elements:** Elements necessary for an organism's survival. * **Water's Composition:** Two hydrogen atoms and one oxygen atom (H₂O). * **pH:** A measure of the acidity or basicity of a solution. * **Elements in Living Matter:** Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N) make up about 96% of living matter. * **DNA and RNA Base Pairing:** * DNA: A-T, T-A, C-G, G-C * RNA: A-U, U-A, C-G, G-C * **Polypeptides:** Chains of amino acids. * **Sickle Cell Anemia:** A genetic disorder caused by a mutation in the gene for hemoglobin. Glutamic acid is replaced by valine. * **DNA Replication:** DNA contains the instructions for its own replication. * **Steroids:** Lipids characterized by a four-fused ring structure. * **Genes:** Units of heredity. * **Purines:** Adenine (A) and Guanine (G). * **Pyrimidines:** Cytosine (C), Thymine (T), and Uracil (U). * **Amino Acids:** Monomers of proteins. Contain an amino group (-NH₂) and a carboxyl group (-COOH). * **Ester Linkage:** The bond formed between a glycerol molecule and a fatty acid in lipids. * **Insulin:** A hormone secreted by the pancreas that regulates blood sugar levels. * **Proteins:** Polymers of amino acids with diverse functions (enzymes, structural components, transport, etc.). * **DNA Strand Orientation:** DNA strands run antiparallel (5' to 3' and 3' to 5'). * **Enzymes:** Proteins that catalyze biochemical reactions. * **Pepsin and Trypsin:** Digestive enzymes. * **Ovalbumin and Casein:** Storage proteins. * **Nitrogenous Bases:** Adenine (A), Thymine (T), Cytosine (C), Guanine (G), and Uracil (U). * **Phospholipids:** Lipids with a phosphate group; crucial components of cell membranes. * **Nucleotides:** Monomers of nucleic acids (DNA and RNA). * **Saturated Fats:** Fats with no double bonds between carbon atoms in their fatty acid chains. * **Waxes:** Lipids found in leaves, flowers, and ears. * **Hemoglobin:** A transport protein that carries oxygen in the blood. * **Thymine:** A pyrimidine base found in DNA but not RNA. * **Spider Silk:** A protein used to make spider webs. * **Fatty Acids:** Long hydrocarbon chains with a carboxyl group at one end. * **Glycerol:** A three-carbon alcohol. * **Unsaturated Fats:** Fats with one or more double bonds between carbon atoms in their fatty acid chains. * **Examples of Steroids:** Cholesterol, testosterone, estradiol. * **Phospholipid Bilayer:** The structure of cell membranes, formed by a double layer of phospholipids. * **Lipids that Provide Energy:** Fats and oils. * **Lipoproteins:** Complexes of lipids and proteins. * **Why Lipids Aren't True Macromolecules:** They lack monomers. This comprehensive review covers a significant portion of the material for your AP Biology 1 final exam. Remember to review your textbook, class notes, and practice problems to solidify your understanding. Good luck!