AP Biology Course Study Guide

Protein & Nucleic Acids

  • Macromolecules:

    • Proteins (Composed of C, H, O, N, S - CHONS):
    • Monomer: Amino Acids
      • Enzymes: Majority of proteins, not all.
      • Structure:
      • Directionality: Amino (NH2) end & Carboxyl (COOH) end.
      • Covalent Bonds: Amino acids are linked through peptide bonds via dehydration synthesis.
      • Varied R Groups: Contribute to properties (hydrophobic, hydrophilic, ionic).
      • Polypeptide Formation:
      • Formation is through peptide bonds in chains.
      • Hydrolysis: Process using water (H2O) to break polypeptides into amino acids.

  • Protein Structure:

    • Primary: Sequence of amino acids determining overall protein shape (peptide bonds).
    • Secondary: Local folding into alpha helices and beta sheets via hydrogen bonds.
    • Tertiary: Overall 3D structure stabilized by hydrogen, disulfide, ionic bonds, and Van der Waals interactions.
    • Quaternary: Multiple polypeptides form a macromolecule; maintains similar bonding as tertiary structure.

  • Nucleic Acids (Composed of C, H, O, P, N - CHOPN):

    • Monomer: Nucleotides (Nitrogenous base + 5-Carbon sugar + Phosphate group).
    • Nucleotides join through covalent bonds via dehydration synthesis; phosphate of one nucleotide bonds to 3′ hydroxyl of another.
    • Hydrogen Bonds in nucleic acid strands facilitate base pairing.

  • Nitrogenous Bases:

    • Purines: Adenine (A), Guanine (G) (two rings).
    • Pyrimidines: Thymine (T), Cytosine (C), and Uracil (U for RNA) (one ring).
    • Base Pairing: Cytosine-Guanine (3 H bonds), Adenine-Thymine (2 H bonds); T-U in RNA.

  • Comparison RNA vs DNA:

    • Both have three components (sugar, phosphate, base), linear structure, polarity marked by 5′ & 3′ ends.
    • DNA: Double-stranded, deoxyribose, T, antiparallel strands.
    • RNA: Single-stranded, ribose, U.

Carbohydrates & Lipids

  • Carbohydrates: Simple formula of 1C:2H:1O; provides energy and serves as a monomer for polysaccharides.
  • Lipids: Formula of 1C:2H: very few Os, hydrophobic, nonpolar.
    • Phospholipids: Amphipathic; essential in cell membranes.

Cellular Organelles & Cell Size

  • Cellular Organelles:

    • Nucleus: Site of DNA and RNA synthesis.

    • Ribosomes: Protein synthesis, made from rRNA, present in all cells.

    • Endoplasmic Reticulum (ER):

    • Rough ER: Site of protein synthesis with ribosomes.

    • Smooth ER: Lipid synthesis and detoxification.

    • Golgi Apparatus: Modifies, sorts, and packages proteins for secretion.

    • Mitochondria: Site of ATP production, contains inner membrane folds for increased surface area;

    • Krebs cycle in the matrix, ETC in the inner membrane.

    • Lysosomes: Contain hydrolytic enzymes for digestion and waste removal.

    • Vacuoles: Storage and maintenance of turgor pressure in plant cells.

    • Chloroplasts: Site of photosynthesis in plant cells, containing thylakoid membranes and stroma.

  • Cell Size:

    • Cells with a high surface area to volume ratio are more efficient.
    • Microvilli can increase the surface area.

Membrane Transport

  • Cell Membrane: Composed of phospholipid bilayer with proteins, steroids, glycoproteins, and glycolipids.
  • Transport Mechanisms:
    • Passive Transport: Movement from high to low concentration; no energy needed.
    • Active Transport: Movement from low to high concentration; requires energy (ATP).
    • Endocytosis: Engulfing molecules through vesicles.
    • Exocytosis: Releasing materials from vesicles.

Tonicity & Osmoregulation

  • Tonicity: Determined by solute concentration; influences water potential.
    • Hypertonic: More solute, less water.
    • Hypotonic: Less solute, more water.
    • Isotonic: Equal concentrations on both sides.

Enzymes

  • Catalysts that lower activation energy and enhance reaction rates.
  • Active Site: Specific to substrates; alters with temperature and pH changes (denaturation).

Photosynthesis & Cellular Respiration

  • Photosynthesis: Converts solar energy into sugars using chloroplasts; includes light-dependent and independent reactions.
    • Calvin cycle occurs in the stroma producing G3P.
  • Cellular Respiration: Generates ATP from glucose via glycolysis, Krebs cycle, and the electron transport chain.
    • Aerobic and anaerobic pathways discussed; importance of electron carriers.

Cell Communication

  • Methods include direct contact (e.g., Plasmodesmata) and signal transduction pathways; include feedback mechanisms (negative and positive feedback).

Cell Cycle & Division

  • Phases: Interphase (G1, S, G2), Mitosis, and checkpoints to monitor cell readiness to proceed.
  • Mitosis produces identical cells; Meiosis produces gametes with genetic variation.

Gene Regulation**

  • Eukaryotic Regulation: Involves more complex processes compared to prokaryotes, including transcription factors and chromatin remodeling.
  • Operons (in Prokaryotes): Such as trp and lac operons that regulate groups of genes coordinately.

Gene Expression**

  • Genetic flow from DNA to mRNA to protein synthesis; includes transcription, mRNA processing, and translation.
  • Common Genetic Code: Evidence of common ancestry among organisms.

Evolution & Experimental Design**

  • Evolutionary concepts like natural selection and genetics.
  • Experimental Design: Includes hypothesis testing through statistical methods such as chi-square analysis for validity.