Biomembrane Structure Quiz
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Questions and Answers

Which type of membrane protein is covalently linked to lipids, such as GPI anchors?

  • Integral Proteins
  • Peripheral Proteins
  • Lipid-Anchored Proteins (correct)
  • Transmembrane Proteins

    • Which of the following is NOT a characteristic of the fluid mosaic model?

  • Dynamic and constantly changing
  • Rigid structure with fixed components (correct)
  • Lateral movement of lipids and proteins
  • Selective permeability

    • Which of the following molecule types is NOT a major component of the lipid bilayer of cell membranes?

  • Nucleic Acids (correct)
  • Sphingolipids
  • Sterols
  • Glycerophospholipids

    • What is the main role of cholesterol in the cell membrane?

    <p>Enhances the fluidity of the membrane at high temperatures but decreases it at low temperatures (D)</p> Signup and view all the answers

    Which of the following statements is TRUE about lipid rafts?

    <p>They are enriched in cholesterol and sphingolipids, and play a role in signal transduction (D)</p> Signup and view all the answers

    Which type of transport across the membrane is NOT energy-dependent?

    <p>Simple diffusion (D)</p> Signup and view all the answers

    What is the primary function of pumps in membrane transport?

    <p>Moving molecules against their concentration gradient using ATP energy (B)</p> Signup and view all the answers

    Which type of active transport system moves sodium ions out of the cell and potassium ions into the cell?

    <p>Na⁺/K⁺ ATPase (D)</p> Signup and view all the answers

    What is the primary function of Na+/K+ ATPase?

    <p>To pump 3 Na+ out and 2 K+ into the cell. (A)</p> Signup and view all the answers

    Which of the following correctly describes symporters?

    <p>They move two molecules in the same direction. (C)</p> Signup and view all the answers

    What role do V-Class pumps play in the cell?

    <p>They help maintain pH levels in lysosomes and endosomes. (A)</p> Signup and view all the answers

    During glycolysis, what is the net gain in ATP per glucose molecule?

    <p>2 ATP (B)</p> Signup and view all the answers

    What is produced during beta-oxidation of fatty acids?

    <p>Acetyl-CoA and FADH₂ (A)</p> Signup and view all the answers

    Which process primarily occurs in the thylakoid membrane during photosynthesis?

    <p>Light-Dependent Reactions (D)</p> Signup and view all the answers

    What intermediate molecule is formed in pyruvate oxidation?

    <p>Acetyl-CoA (D)</p> Signup and view all the answers

    In the action potential, what is the result of the opening of Na+ channels?

    <p>There is an influx of Na+ ions into the cell. (C)</p> Signup and view all the answers

    Flashcards

    Fluid Mosaic Model

    Describes the plasma membrane structure as a fluid combination of lipids, proteins, and carbohydrates.

    Plasma Membrane

    A semi-permeable barrier composed of a lipid bilayer, proteins, and carbohydrates that regulates substance movement.

    Integral Proteins

    Proteins that span the entire lipid bilayer and are involved in transport and communication.

    Passive Transport

    Movement of substances across the membrane without using energy, including simple and facilitated diffusion.

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    Active Transport

    Movement of substances against their gradient using energy (usually ATP), such as Na+/K+ ATPase.

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    Lipid Bilayer

    A double layer of lipids in the membrane with hydrophilic heads facing out and hydrophobic tails facing in.

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    Endocytosis

    Process by which cells take in substances by enclosing them in a membrane vesicle.

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    Uniporters

    Transporters that carry a single molecule down its concentration gradient, e.g., GLUT1 for glucose.

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    Symporters

    Transport proteins that move two molecules in the same direction.

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    Na+/K+ ATPase

    P-Class pump that moves 3 Na+ out and 2 K+ in per cycle.

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    Action Potential

    Electrical signal changes in a neuron involving depolarization and repolarization.

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    Glycolysis

    The process of converting glucose into 2 pyruvate, producing 2 ATP and 2 NADH.

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    Citric Acid Cycle

    The cycle that processes Acetyl-CoA to generate NADH, FADH₂, and ATP.

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    Light-Dependent Reactions

    Reactions that occur in the thylakoid membrane, producing O₂ and NADPH.

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    Calvin Cycle

    The process in the stroma of chloroplasts that fixes CO₂ into G3P.

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    Study Notes

    Biomembrane Structure

    • Plasma membranes (PM) are composed of lipid bilayers, proteins, and carbohydrates
    • They act as a semi-permeable barrier, controlling substance movement
    • The fluid mosaic model describes lateral movement of lipids and proteins within the membrane
    • Membrane proteins are categorized as:
      • Integral (transmembrane): Span the bilayer
      • Peripheral: Attached via non-covalent interactions
      • Lipid-anchored: Covalently linked to lipids (e.g., GPI anchors)
    • Lipid bilayers have hydrophilic heads facing outward and hydrophobic tails inward
    • Cholesterol regulates fluidity and stability
    • Membrane lipids include phospholipids (e.g., phosphatidylcholine, phosphatidylserine), sphingolipids (e.g., sphingomyelin, glycolipids, ceramides), and sterols (e.g., cholesterol, phytosterols)
    • Membrane asymmetry exists with different lipid compositions in cytosolic vs. extracellular leaflets
    • Lipid distribution is regulated by flipases, floppases, and scramblases
    • Membranes exhibit self-sealing and fusion properties, facilitating vesicle formation, endocytosis, and exocytosis
    • Lateral diffusion allows lipids and proteins to move within the membrane
    • Phase transitions (gel to fluid state) depend on temperature
    • Lipid rafts are specialized regions enriched with cholesterol and sphingolipids for signaling and trafficking

    Transmembrane Transport of Ions and Small Molecules

    • Pumps (primary active transport) use ATP to move molecules against gradients
    • Channels allow specific ion passage down electrochemical gradients
    • Transporters (carriers) undergo conformational changes to move molecules
    • Transporter types include:
      • Uniporters: Transport a single molecule down its gradient (e.g., GLUT1 for glucose)
      • Symporters: Move two molecules in the same direction (e.g., Na+/glucose symporter)
      • Antiporters: Move two molecules in opposite directions (e.g., Na+/H+ exchanger)
    • ATP-powered transport proteins include:
      • P-class pumps (e.g., Na+/K+ ATPase, Ca2+ ATPase)
      • V-class pumps (acidify organelles)
      • F-class pumps (ATP synthase)
      • ABC transporters (multidrug resistance, CFTR)
    • Resting membrane potential is approximately -70 mV, maintained by Na+/K+ ATPase and K+ leak channels
    • Voltage-gated ion channels open/close in response to voltage changes (e.g., Na+, K+, Ca2+) for action potentials

    Cellular Energetics

    • Aerobic respiration uses O2 as the final electron acceptor in the electron transport chain
    • Anaerobic respiration uses alternative electron acceptors (e.g., sulfate, nitrate)
    • Cellular respiration's overall equation: C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + 30-32 ATP
    • Stages of glucose oxidation include Glycolysis (cytoplasm), Pyruvate oxidation (mitochondrial matrix), Citric Acid Cycle (TCA cycle), and Electron Transport Chain & Oxidative Phosphorylation
    • Lipid oxidation (beta-oxidation) breaks down fatty acids into acetyl-CoA, NADH, and FADH2
    • Protein catabolism deaminates amino acids, allowing them to enter the TCA cycle
    • Photosynthesis involves light-dependent reactions (split water, producing O2 and protons, reducing NADP+ to NADPH) and Calvin cycle (fixing CO2 into glyceraldehyde-3-phosphate (G3P))

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    Related Documents

    BIOL 408 Exam Study Guide PDF

    Description

    Test your knowledge on the structure and function of biomembranes. This quiz covers key concepts such as the lipid bilayer composition, fluid mosaic model, types of membrane proteins, and the roles of cholesterol. Challenge yourself on how these elements contribute to cellular functionality and membrane dynamics!

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