AP Biology Exam Review Flashcards

UNIT 1: CHEMISTRY OF LIFE

• Bonds

  • Ionic Bonds: Formed when electrons are transferred from one atom to another.
  • Covalent Bonds: Electrons are shared between atoms.
  • Hydrogen Bonds: Interactions between hydrogen and electronegative atoms (e.g., O, N).

• Electronegativity: An atom's attraction for electrons in a covalent bond. Stronger electronegativity leads to polar bonds.

  • Example: In DNA, G-C pairs have 3 hydrogen bonds, while A-T pairs have 2.

• Properties of Water:

  • Adhesion: Water molecules sticking to other surfaces.
  • Cohesion: Water molecules sticking to each other.
  • Capillary Action: Combined action of adhesion and cohesion (e.g., water moving up a tree).
  • High Specific Heat: Requires a lot of energy to change temperature.
  • Surface Tension: Refers to the cohesive forces at the water's surface (e.g., water strider insects).

MACROMOLECULES

• Four Main Types:

  1. Carbohydrates (C, H, O in a 1:2:1 ratio)
  • Structural (Cellulose) and Storage (Starch).
  • Monosaccharides: Simple sugars (e.g., glucose).
  • Polysaccharides: Linked monosaccharides, providing energy storage.
  1. Proteins (C, H, O, N, S)
  • Made of Amino Acids (20 types, determined by R groups).
  • Enzymes: Proteins that speed up reactions.
  • Structure Levels:
    • Primary: Sequence of amino acids.
    • Secondary: Coiling (alpha helix) or folding (beta sheet).
    • Tertiary: Overall 3D shape from side chain interactions.
    • Quaternary: Assembly of multiple polypeptides.
  1. Nucleic Acids (C, H, O, N, P, S)
  • Composed of Nucleotides (5-carbon sugar, phosphate group, nitrogen base).
  • DNA: Contains deoxyribose; pairs adenine (A) with thymine (T) and cytosine (C) with guanine (G).
  • RNA: Contains ribose; uses uracil (U) instead of thymine.
  1. Lipids (C, H, O)
  • Diverse group including Triglycerides, Phospholipids, and Steroids.
  • Phospholipids have hydrophilic heads and hydrophobic tails; form cell membranes.

CELL STRUCTURE AND FUNCTION

• Cell Types:

  • Eukaryotic: Membrane-bound organelles; DNA in the nucleus.
  • Prokaryotic: No membrane-bound organelles; DNA in cytoplasm.

• Essential Components:

  1. Ribosomes: Protein-synthesizing structures made of rRNA and proteins.
  2. Plasma Membrane: Selectively permeable barrier controlling substance entry/exit.
  3. Organelles:
  • Endoplasmic Reticulum (Smooth ER and Rough ER): Involved in lipid synthesis and protein transport.
  • Nucleus: Contains genetic info; site of RNA synthesis.
  • Golgi Complex: Modifies, packages proteins for transport.
  • Mitochondria: Powerhouse, ATP production; has own DNA.
  • Plant Cell Structures: Vacuoles (storage) and chloroplasts (photosynthesis).

CELL TRANSPORT MECHANISMS

• Transport Types:
  • Passive Transport: No energy expenditure; substances move down concentration gradients (e.g., diffusion).
  • Active Transport: Requires energy (ATP) to move substances against the gradient.
  • Endocytosis: Cell takes in substances by vesicle formation.
  • Types include Phagocytosis (cell eating) and Pinocytosis (cell drinking).
  • Exocytosis: Taking substances out of the cell via vesicles.

CELL CYCLE AND REGULATION

• Phases:
  • M Phase: Mitosis and cytokinesis.
  • Interphase: Growth phases (G1, S for DNA synthesis, G2).
  • Checkpoints: Regulate the cycle; G1 checks size, G2 checks DNA integrity, and M checks mitosis completion.
• Cancer: Unregulated cell growth; often results from mutations in proto-oncogenes or tumor suppressor genes.

HEREDITY AND GENETICS

• Mendelian Genetics:

  • Traits passed from parents to offspring via alleles.
  • Dominant and Recessive traits; ratios can be predicted (3:1 in monohybrid crosses).
  • Independent Assortment and Linked Genes can alter inheritance patterns.

• Non-Mendelian Genetics:

  • Codominance, incomplete dominance; genetic disorders like cystic fibrosis.
  • Population Genetics: Study of alleles in populations; the Hardy-Weinberg principle describes genetic equilibrium.