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Cellular Respiration and Fermentation

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  • What is cellular respiration?

    Cellular respiration is the process by which cells convert glucose and oxygen into energy (ATP), carbon dioxide, and water.

  • What are the main stages of cellular respiration?

    The main stages are glycolysis, the citric acid cycle (Krebs cycle), and oxidative phosphorylation.

  • Where does glycolysis occur in the cell?

    Glycolysis occurs in the cytoplasm of the cell.

  • What are the products of glycolysis?

    Glycolysis produces 2 ATP, 2 NADH, and 2 pyruvate molecules per glucose molecule.

  • What happens to pyruvate after glycolysis if oxygen is present?

    Pyruvate enters the mitochondria and is converted to acetyl-CoA to enter the citric acid cycle.

  • What is the citric acid cycle?

    The citric acid cycle is a series of chemical reactions in the mitochondrial matrix that produce NADH, FADH2, and ATP by oxidizing acetyl-CoA.

  • What are the main products of the citric acid cycle per glucose molecule?

    Per glucose, the cycle produces 6 NADH, 2 FADH2, 2 ATP, and releases 4 CO2.

  • What is oxidative phosphorylation?

    Oxidative phosphorylation uses electrons from NADH and FADH2 to create a proton gradient that drives ATP synthesis in the mitochondria.

  • Where does oxidative phosphorylation occur?

    It occurs across the inner mitochondrial membrane.

  • What is the role of the electron transport chain (ETC)?

    The ETC transfers electrons from NADH and FADH2 to oxygen, pumping protons to create a gradient for ATP synthesis.

  • What is the final electron acceptor in cellular respiration?

    Oxygen is the final electron acceptor, forming water when it combines with electrons and protons.

  • How many ATP molecules are produced per glucose molecule in cellular respiration?

    Approximately 30-32 ATP molecules are produced per glucose molecule.

  • What is fermentation?

    Fermentation is an anaerobic process that regenerates NAD+ by converting pyruvate into other products, allowing glycolysis to continue without oxygen.

  • Name two common types of fermentation.

    Two common types are lactic acid fermentation and alcoholic fermentation.

  • What is produced in lactic acid fermentation?

    Pyruvate is converted into lactic acid, regenerating NAD+ for glycolysis.

  • What organisms commonly use alcoholic fermentation?

    Yeasts and some bacteria use alcoholic fermentation, producing ethanol and CO2.

  • Why is NAD+ regeneration important in fermentation?

    It allows glycolysis to continue producing ATP when oxygen is absent by maintaining the supply of NAD+.

  • Compare ATP yield of fermentation vs cellular respiration.

    Fermentation yields only 2 ATP per glucose, while cellular respiration yields about 30-32 ATP.

  • What is substrate-level phosphorylation?

    Substrate-level phosphorylation is the direct synthesis of ATP from ADP during glycolysis and the citric acid cycle.

  • What is chemiosmosis?

    Chemiosmosis is the process where ATP synthase uses a proton gradient to produce ATP during oxidative phosphorylation.