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Cellular Respiration and Fermentation

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Termini in questo insieme (24)

  • What is the primary function of mitochondria?
    Mitochondria produce energy in the form of ATP through cellular respiration.
  • Describe the structure of the mitochondrial outer membrane.
    The outer membrane is a lipid bilayer rich in proteins (50-60%) and porins, making it permeable to ions and molecules under 10 KDa.
  • What is the role of the intermembrane space in mitochondria?
    It contains protons (H+) important for cellular respiration and cytochrome c molecules involved in apoptosis.
  • How does the inner mitochondrial membrane differ from the outer membrane?
    The inner membrane has 80% proteins, low permeability, contains cristae, and hosts transporters and enzymatic complexes.
  • What components are found in the mitochondrial matrix?
    The matrix contains mito-ribosomes, circular DNA, mRNA, tRNA, and enzymes for pyruvate oxidation, fatty acid oxidation, and the citric acid cycle.
  • What is unique about mitochondrial DNA (mtDNA)?
    mtDNA is circular, lacks histones, has a slightly different genetic code, is maternally inherited, and exists in 5-10 copies per mitochondrion.
  • What is mitochondrial biogenesis?
    The process of forming new mitochondria from pre-existing ones, involving fusion and fission to maintain mitochondrial function.
  • Define catabolic pathways in cellular respiration.
    Catabolic pathways break down organic molecules, releasing energy by oxidation to produce ATP.
  • What is the difference between aerobic and anaerobic respiration?
    Aerobic respiration uses O2 as the final electron acceptor, while anaerobic respiration uses other electronegative molecules.
  • Explain redox reactions in cellular respiration.
    Redox reactions transfer electrons; oxidation is loss of electrons, reduction is gain. Electrons move from fuel molecules to electron carriers.
  • What role does NAD+ play in cellular respiration?
    NAD+ acts as an electron acceptor, becoming NADH, which stores energy used later to synthesize ATP.
  • How does the electron transport chain function?
    It passes electrons through protein complexes in the inner membrane, releasing energy to pump protons and ultimately reduce O2 to water.
  • What is chemiosmosis in mitochondria?
    Chemiosmosis uses the proton gradient created by the electron transport chain to drive ATP synthesis via ATP synthase.
  • How many ATP molecules are produced per glucose molecule in cellular respiration?
    Up to 32 ATP molecules are produced per glucose molecule through glycolysis, citric acid cycle, and oxidative phosphorylation.
  • What is substrate-level phosphorylation?
    Direct synthesis of ATP by transferring a phosphate group from an organic substrate to ADP during glycolysis and the citric acid cycle.
  • Describe glycolysis.
    Glycolysis breaks down glucose into two pyruvate molecules in the cytoplasm, producing 2 ATP and 2 NADH, and can occur with or without oxygen.
  • What happens to pyruvate before entering the citric acid cycle?
    Pyruvate is oxidized to acetyl CoA by the pyruvate dehydrogenase complex, releasing CO2 and producing NADH.
  • Summarize the citric acid cycle.
    The cycle oxidizes acetyl CoA to CO2 in the mitochondrial matrix, generating 1 ATP, 3 NADH, and 1 FADH2 per turn.
  • What is the proton-motive force?
    The electrochemical gradient of protons across the inner mitochondrial membrane that drives ATP synthesis.
  • How do fermentation and anaerobic respiration differ from aerobic respiration?
    Fermentation regenerates NAD+ without an electron transport chain; anaerobic respiration uses electron acceptors other than O2; aerobic respiration uses O2.
  • Name two common types of fermentation.
    Alcohol fermentation (produces ethanol and CO2) and lactic acid fermentation (produces lactate without CO2).
  • Why is NAD+ regeneration important in fermentation?
    It allows glycolysis to continue by accepting electrons, enabling ATP production without oxygen.
  • What is the net ATP yield of fermentation per glucose molecule?
    Fermentation yields 2 ATP per glucose molecule via substrate-level phosphorylation.
  • How is ATP synthase powered?
    ATP synthase is powered by the flow of protons down their gradient through the enzyme, synthesizing ATP from ADP and phosphate.