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Biochemistry: Cellular Structure, Energy, and Oxygen Transport

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Termini in questo insieme (20)

  • What are monomers and polymers in cellular biochemistry?
    Monomers are small molecules that join to form polymers, which are large macromolecules essential for cellular structure and function.
  • Difference between prokaryotic and eukaryotic cells?
    Prokaryotic cells lack a nucleus and have a single circular chromosome; eukaryotic cells have a nucleus and multiple linear chromosomes.
  • What is the plasma membrane's role in a cell?
    The plasma membrane surrounds the cell, maintaining homeostasis by regulating nutrient and ion transport and enabling energy conversion.
  • State the First Law of Thermodynamics in biological systems.
    Energy cannot be created or destroyed, only transformed from one form to another, maintaining total energy constant.
  • What does the Second Law of Thermodynamics imply for living cells?
    Energy transfer increases entropy (disorder), so living cells require constant energy input to maintain order.
  • Define Gibbs free energy change (ΔG) and its significance.
    ΔG is the energy available to do work; ΔG<0 means spontaneous (exergonic), ΔG>0 means non-spontaneous (endergonic).
  • How is ATP hydrolysis coupled to cellular reactions?
    ATP hydrolysis releases energy (exergonic) that drives endergonic reactions like macromolecule synthesis by sharing intermediates.
  • What is metabolism and its two main types?
    Metabolism includes catabolism (breaking down molecules to generate ATP) and anabolism (using ATP to build macromolecules).
  • What is the role of photosynthesis in energy conversion?
    Photosynthesis converts light energy into chemical energy (ATP) used for carbon fixation to synthesize glucose.
  • Describe the oxygen-evolving complex in photosystem II.
    The Mn4CaO5 cluster catalyzes water splitting, releasing O2 and protons during photosynthesis.
  • What is the function of the mitochondrial electron transport chain?
    It transfers electrons from NADH to oxygen, pumping protons to generate ATP via oxidative phosphorylation.
  • How are reactive oxygen species (ROS) neutralized in cells?
    Enzymes like superoxide dismutase, catalase, and glutathione peroxidase detoxify ROS to prevent cellular damage.
  • Why are globin proteins important for oxygen transport?
    Globins like myoglobin and hemoglobin bind oxygen reversibly, facilitating oxygen storage and transport in tissues.
  • What is the structural difference between myoglobin and hemoglobin?
    Myoglobin is a single polypeptide with one heme; hemoglobin is a tetramer with four subunits, each containing a heme.
  • Explain the cooperative oxygen binding of hemoglobin.
    Hemoglobin's quaternary structure allows oxygen binding at one site to increase affinity at others, producing a sigmoid oxygen dissociation curve.
  • What is the Bohr effect in hemoglobin function?
    Lower pH (higher H+ concentration) decreases hemoglobin's oxygen affinity, promoting oxygen release in tissues.
  • How does 2,3-bisphosphoglycerate (2,3-BPG) regulate hemoglobin?
    2,3-BPG binds hemoglobin's T state, stabilizing it and decreasing oxygen affinity to facilitate oxygen release.
  • Why does fetal hemoglobin have higher oxygen affinity than adult hemoglobin?
    Fetal hemoglobin binds 2,3-BPG less tightly, resulting in higher oxygen affinity to extract oxygen from maternal blood.
  • What causes sickle cell anemia at the molecular level?
    A point mutation substituting valine for glutamate at position 6 in β-globin causes hemoglobin polymerization and red cell sickling.
  • How does hydroxyurea help treat sickle cell anemia?
    Hydroxyurea increases fetal hemoglobin levels, which inhibits sickle hemoglobin polymerization and reduces symptoms.