AP Biology Review Notes

AP Biology Review Notes

Unit 1: Chemistry of Life

  • Carbohydrates: Composed of Carbon (C), Hydrogen (H), & Oxygen (O); Ratio: 1:2:1.

    • Monomer: Monosaccharide
    • Examples: Glucose, Fructose, Galactose.
    • Structural forms:
      • Cellulose: Found in plant cell walls.
      • Chitin: Found in fungi cell walls & exoskeleton of arthropods.
    • Storage Forms:
    • Starch: Found in plants.
    • Glycogen: Found in animals.
    • Comparison:
    • Starch vs. Cellulose (1-4 linkage of glucose monomers).

  • Proteins: Composed of C, H, O, N, & S.

    • Monomer: Amino Acid.
    • Structure Levels:
    • Primary: Sequence of amino acids.
    • Secondary: Alpha helix or beta pleated sheet due to hydrogen bonds between backbone.
    • Tertiary: Final 3D structure formed by various bonds (hydrogen, ionic, covalent, etc.) between R groups.
    • Quaternary: Interaction between multiple polypeptide chains.
    • Bond: Peptide bond between carboxyl & amino groups.

  • Lipids: Composed of C, H, O, & P (in phospholipids).

    • Structure includes phospholipids and fatty acids. Nonpolar in nature.
    • Types: Fats, Steroids.
    • Saturation:
    • Saturated: All single bonds; saturated with hydrogen.
    • Unsaturated: At least one double bond; hydrogens are not maximal.

Unit 2: The Cell

  • Nucleus:

    • Structure: Double membrane with pores.
    • Functions: Storage of genetic information (DNA), synthesis of RNA, ribosome subunit assembly.

  • Endoplasmic Reticulum (ER):

    • Rough ER:
    • Structure: Membrane with ribosomes.
    • Functions: Synthesis of membrane-bound proteins and secreted proteins, mechanical support.
    • Smooth ER:
    • Structure: Folded, tubelike structure.
    • Functions: Lipid synthesis, detoxification, calcium storage.

  • Golgi Complex: Membrane structure responsible for folding, chemical modification, and packaging of proteins.

  • Mitochondria:

    • Structure: Double membrane with inner folds (cristae).
    • Functions: Site of oxidative phosphorylation and Krebs cycle.

  • Plasma Membrane:

    • Composed of phospholipids, membrane proteins, cholesterol, glycolipids, and glycoproteins.
    • Transport Mechanisms:
    • Simple Diffusion: Passive, does not require energy.
    • Facilitated Diffusion: Passive, requires transport proteins.
    • Active Transport: Requires energy, moves against concentration gradient.

  • Osmosis: Movement of water from high to low water potential across a semi-permeable membrane.

    • Solution Types:
    • Hypertonic: High solute concentration.
    • Isotonic: Equal solute concentration.
    • Hypotonic: Low solute concentration.

Unit 3: Cellular Energetics

  • Gibbs Free Energy:

    • Endergonic Reaction: $ΔG > 0$; absorbs energy.
    • Example: $ADP + P_i
      ightarrow ATP$.
    • Exergonic Reaction: $ΔG < 0$; releases energy.
    • Example: $ATP
      ightarrow ADP + P_i$.

  • Cellular Respiration:

    • Glycolysis: Location - Cytosol; Products: 2 Pyruvate, 2 NADH, 2 ATP.
    • Krebs Cycle: Location - Mitochondrial Matrix; Products: 2 CO₂, 3 NADH, 1 FADH₂, 1 ATP.
    • Oxidative Phosphorylation: Uses NADH and FADH₂ to create ATP via chemiosmosis.

Unit 4/5: Cellular Communication & Cell Cycle

  • Cellular Communication: Process of signaling involving reception, transduction, and response.

    • Reception: Ligands bind receptors, causing shape changes.
    • Transduction: Signaling cascades relay signals, often amplifying them.
    • Response: Changes in gene expression, secretion of molecules, apoptosis.

  • Cell Cycle Phases:

    • Mitosis: Division of nucleus (Prophase, Metaphase, Anaphase, Telophase, Cytokinesis).
    • Meiosis: Results in four haploid cells; involves crossing over and independent assortment.

Unit 6: Heredity & Molecular Genetics

  • Inheritance Patterns:

    • Complete Dominance: Homozygous dominant and heterozygous exhibit the same phenotype.
    • Codominance: Both traits expressed in heterozygous individuals.
    • Incomplete Dominance: Intermediate phenotype in heterozygous individuals.

  • Central Dogma: DNA → RNA → Protein.

    • Transcription: RNA synthesis from DNA.
    • RNA polymerase reads template strand 3’ to 5’.
    • Translation: mRNA to protein using ribosomes.

Unit 7: Natural Selection

  • Natural Selection: Process where organisms with favorable traits survive and reproduce, passing traits to next generations.
    • Types of Selection:
    • Stabilizing, Directional, Disruptive Selection.

Unit 8: Ecology

  • Ecosystem Dynamics: Study of energy flow and nutrient cycling within ecosystems.
    • Trophic Levels: Producers, consumers, decomposers.
    • Population Ecology: Factors affecting population size (density-dependent and independent).