AP Bio unit 3

Mechanisms in AP Biology Unit 3

  1. Photosynthesis

    • Definition: The process by which green plants, algae, and some bacteria convert light energy into chemical energy in the form of glucose.

    • Mechanisms:

      • Light-dependent reactions: Occur in the thylakoid membranes and convert light energy to chemical energy (ATP and NADPH).

      • Calvin Cycle (Light-independent reactions): Takes place in the stroma, using ATP and NADPH to fix CO2 into glucose.

  2. Cellular Respiration

    • Definition: The process by which living organisms convert glucose and oxygen into energy (ATP), carbon dioxide, and water.

    • Mechanisms:

      • Glycolysis: Breakdown of glucose to pyruvate, producing a small amount of ATP.

      • Krebs Cycle: Uses acetyl-CoA to produce electron carriers and CO2.

      • Electron Transport Chain (ETC): Uses electrons from NADH and FADH2 to create a proton gradient, generating ATP through oxidative phosphorylation.

  3. Enzyme Activity

    • Definition: Enzymes are biological catalysts that speed up chemical reactions.

    • Mechanisms:

      • Active site binding: Substrates bind to enzyme active sites, forming enzyme-substrate complexes.

      • Enzyme regulation: Includes competitive and non-competitive inhibition, and allosteric regulation.

  4. Cell Communication

    • Definition: The process by which cells in a multicellular organism communicate with each other.

    • Mechanisms:

      • Signal transduction pathways: Involves a series of molecular events triggered by a signal molecule (ligand) binding to a receptor, leading to a cellular response.

Important Terms and Definitions

  • ATP (Adenosine Triphosphate): The primary energy carrier in cells.

  • Chloroplast: The organelle in plant cells where photosynthesis occurs.

  • Mitochondria: The organelle in eukaryotic cells where cellular respiration takes place.

  • NADH/NADPH: Electron carriers involved in cellular respiration and photosynthesis respectively.

  • Glycolysis: The process of breaking down glucose to produce energy (ATP) in the absence of oxygen.

  • Signal Transduction: The process by which a cell responds to signals in its environment, involving multiple steps and molecular interactions.