Respiration

• What are the four key stages of respiration?

  Glycolysis, link reaction, Krebs cycle, oxidative phosphorylation
• Where does glycolysis occur in the cell?

  In the cytoplasm
• Does glycolysis require oxygen?

  No, it occurs in anaerobic respiration
• What is the first step of glycolysis?

  Glucose is phosphorylated to glucose phosphate
• How many ATP molecules are used to phosphorylate glucose in glycolysis?

  Two ATP molecules
• What is produced when triose phosphate is oxidized?


  Pyruvate, 4 ATP, and reduced NAD
• What is the net gain of ATP in glycolysis?

  Two ATP molecules
• What happens to pyruvate after glycolysis?

  It is transported to the mitochondrial matrix
• What is produced during the link reaction from pyruvate?

  Acetate and reduced NAD
• What does acetate combine with to enter the Krebs cycle?

  Coenzyme A
• How many times does the link reaction occur for one glucose molecule?

  Twice
• What is produced in the Krebs cycle per cycle?

  Three reduced NAD, one reduced FAD, one ATP, and two carbon dioxides
• How many ATP molecules are produced from two rounds of the Krebs cycle?

  Two ATP molecules
• What is the final step of respiration?

  Oxidative phosphorylation
• What is the role of oxygen in oxidative phosphorylation?

  It is the final electron acceptor
• How is ATP produced during oxidative phosphorylation?

  Through facilitated diffusion via ATP synthase
• How many ATP molecules are produced in oxidative phosphorylation?

  34 ATP molecules
• What is produced as a byproduct of oxidative phosphorylation?

  Water
• What does anaerobic respiration produce in animals?

  Lactate or lactic acid
• Why does anaerobic respiration occur?

  To re-oxidize NAD for glycolysis
• What is the downside of lactic acid production in anaerobic respiration?

  It can denature enzymes and proteins
• What do microbes produce during anaerobic respiration?

  Ethanol and carbon dioxide
• Why is ethanol harmful in anaerobic respiration?

  It can inhibit metabolic processes
• What is the first stage of aerobic respiration?

  Glycolysis
• Where do the link reaction and Krebs cycle occur?

  Mitochondrial matrix
• What must be transported from the cytoplasm to the mitochondrial matrix?

  Pyruvate and reduced NAD (NADH)
• What happens to pyruvate in the link reaction?

  It is oxidized into acetate
• What is lost from pyruvate during its oxidation?

  Hydrogen
• What does NAD do during the link reaction?

  It picks up hydrogen and becomes NADH
• What is the three-carbon molecule produced from glycolysis?

  Pyruvate
• What is the purpose of converting acetate into acetyl CoA?

  To enter the Krebs cycle
• What are the three products of the link reaction?

  Acetyl CoA, carbon dioxide, and NADH
• How many times does the link reaction occur for one glucose molecule?

  Twice
• What does acetyl CoA react with in the Krebs cycle?

  A four-carbon molecule
• What happens to the six-carbon molecule during the Krebs cycle?

  It loses carbon and becomes a four-carbon molecule
• What are the products of one round of the Krebs cycle?

  Three NADH, one FADH2, one ATP, two CO2
• How many times does the Krebs cycle occur for one glucose molecule?

  Twice
• What are the key stages of aerobic respiration discussed?

  • Glycolysis (anaerobic)
  • Link reaction
  • Krebs cycle (citric acid cycle)
• What is the relationship between the link reaction and Krebs cycle?

  • Link reaction converts pyruvate to acetyl CoA
  • Acetyl CoA enters Krebs cycle
  • Both occur in mitochondrial matrix
• What is the role of coenzymes in the link reaction and Krebs cycle?

  • NAD reduces to NADH by gaining hydrogen
  • FAD reduces to FADH2 by gaining hydrogen
  • Coenzyme A helps transport acetate