AP Biology Review Notes

AP Biology Review: One Pagers by @marcolearning & @apbiopenguins

Unit 1: Chemistry of Life

Carbohydrates

  • Composed of C, H, & O in a 1:2:1 ratio.
  • Monomer: Monosaccharide (e.g., Glucose, Fructose, Galactose).
  • Disaccharides: Two monosaccharides linked by a Glycosidic Linkage (e.g., Sucrose, Lactose, Maltose).
  • Structural examples: Cellulose (found in plant cell walls), Chitin (found in fungi cell walls & exoskeleton of arthropods).
  • Storage examples: Starch (found in plants), Glycogen (found in animals).
  • Starch vs. Cellulose: Differ in the linkage of glucose monomers. Starch has 1-4 linkage of α glucose monomers, while cellulose has 1-4 linkage of β glucose monomers.

Proteins

  • Composed of C, H, O, N, & S.
  • Monomer: Amino Acid.
  • Bond: Peptide bond (between carboxyl & amino groups).
  • Structure:
    • Primary: String of amino acids.
    • Secondary: Alpha helix or beta pleated sheet, stabilized by hydrogen bonds between the backbones.
    • Tertiary: Final 3D structure, stabilized by ANY bonds (hydrogen, covalent, ionic, …) between R groups.
    • Quaternary: Arrangement of multiple polypeptides, stabilized by ANY bonds (hydrogen, covalent, ionic, …) between R groups of different polypeptides.
  • R groups can be hydrophilic (exterior), hydrophobic (interior), or charged.

Lipids

  • Composed of C, H, O, & P (in phospholipids).
  • Monomer: N/A.
  • All lipids are NONPOLAR.
  • Fats: Glycerol + 3 fatty acids.
  • Phospholipids: Phosphate + Glycerol + 2 fatty acids. Amphipathic (have both hydrophilic and hydrophobic regions).
    • Hydrophilic head (phosphate) attracted to water.
    • Hydrophobic tail (fatty acids) repelled by water.
  • Steroids: Four fused rings (e.g., cholesterol).
  • Saturated fatty acids: ALL single bonds (each carbon is SATURATED by hydrogen).
  • Unsaturated fatty acids: At least one double bond (not all carbons are SATURATED by hydrogen).

Nucleic Acids

  • Composed of C, H, O, N, & P.
  • Monomer: Nucleotide.
  • Nucleotide Structure: Phosphate, Pentose Sugar, Nitrogenous Base.
  • Nitrogenous Bases:
    • Purines (double ring): Adenine (A) & Guanine (G).
    • Pyrimidines (single ring): Cytosine (C), Thymine (T), Uracil (U).
  • Base Pairing: A & T (2 hydrogen bonds), C & G (3 hydrogen bonds).
  • Pentose Sugar: Deoxyribose (DNA) or Ribose (RNA).
  • Bond: Phosphodiester linkage (between phosphate and hydroxyl).
  • Directionality: 5' → 3'; antiparallel.
  • DNA vs. RNA:
    • Nitrogenous Bases: A, T, C, G (DNA); A, U, C, G (RNA).
    • Sugar: Deoxyribose (DNA); Ribose (RNA).
    • Strandedness: