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General Biology: Membranes, Metabolism, Respiration, Photosynthesis, and Cell Cycle

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  • What is the plasma membrane's basic structure?
    A phospholipid bilayer containing membrane proteins.
  • Which phospholipid regions are hydrophilic vs. hydrophobic?
    Heads are hydrophilic; fatty-acid tails are hydrophobic.
  • What membrane model describes proteins within a fluid lipid bilayer?
    The fluid mosaic model.
  • What does cholesterol do in an animal cell membrane?
    It buffers membrane fluidity across temperature changes.
  • What is passive transport?
    Movement down a gradient without cellular energy.
  • What is active transport?
    Energy-driven movement against a concentration gradient.
  • What is facilitated diffusion?
    Passive transport through a membrane protein.
  • What is osmosis?
    Diffusion of water across a selectively permeable membrane.
  • During osmosis, water moves toward which side?
    The side with the higher solute concentration.
  • What happens to an animal cell in a hypertonic solution?
    It loses water and shrivels.
  • What happens to a plant cell in a hypotonic solution?
    It becomes turgid; the cell wall prevents bursting.
  • What is plasmolysis?
    Water loss causes the plant membrane to pull from the cell wall.
  • What are aquaporins?
    Membrane channel proteins that rapidly transport water.
  • What does the first law of thermodynamics state?
    Energy is conserved; it can be transferred or transformed.
  • What does the second law of thermodynamics state?
    Energy transformations increase the universe's entropy.
  • What does negative ΔG mean?
    The reaction is exergonic and thermodynamically spontaneous.
  • What does ATP hydrolysis produce?
    ADP + Pi and released free energy.
  • What do enzymes lower?
    Activation energy.
  • Do enzymes change a reaction's ΔG?
    No; they change reaction rate, not ΔG.
  • What is an enzyme's active site?
    The region where substrate binds and catalysis occurs.
  • What is feedback inhibition?
    A pathway's end product inhibits an earlier enzyme.
  • What is the first stage of cellular respiration?
    Glycolysis.
  • Where does glycolysis occur?
    The cytosol.
  • What are glycolysis's products per glucose?
    2 pyruvate, 2 NADH, and net 2 ATP.
  • Where does the citric acid cycle occur in eukaryotes?
    The mitochondrial matrix.
  • What is aerobic respiration's final electron acceptor?
    Oxygen (O2).
  • What directly powers ATP synthase?
    H+ flowing down its electrochemical gradient.
  • What is chemiosmosis?
    Using an H+ gradient to drive ATP synthesis.
  • Where do photosynthesis's light reactions occur?
    The thylakoid membranes.
  • Where does the Calvin cycle occur?
    The chloroplast stroma.
  • What does rubisco catalyze?
    Attachment of CO2 to RuBP.
  • What is photorespiration?
    Rubisco uses O2 instead of CO2, wasting energy.
  • What phase follows G1?
    S phase.
  • What occurs during S phase?
    DNA replication.
  • What happens during metaphase?
    Chromosomes align at the metaphase plate.
  • What is the mitotic spindle's primary role?
    Separating duplicated chromosomes.
  • How does animal-cell cytokinesis occur?
    A cleavage furrow pinches the cell in two.
  • What two components form active MPF?
    Cyclin and Cdk.
  • What feature is shared by all cancers?
    Escape from normal cell-cycle controls.