Link Reaction

• What is the end product of glycolysis?

  Pyruvate
• Why is pyruvate important in respiration?

  It contains a substantial amount of chemical energy that can be further utilized to produce more ATP
• What happens to pyruvate when oxygen is available?

  It enters the mitochondrial matrix and aerobic respiration continues
• How does pyruvate move into the mitochondria?

  It moves via active transport
• What is required for pyruvate to cross the mitochondrial membrane?

  A transport protein and a small amount of ATP
• What reaction does pyruvate participate in once in the mitochondrial matrix?

  The link reaction
• Why is it called the link reaction?

  Because it links glycolysis to the Krebs cycle
• What are the steps of the link reaction?

  1. Pyruvate is oxidized to produce acetate and carbon dioxide, reducing NAD to NADH.
  2. Acetate combines with coenzyme A to form acetyl CoA.
• What are the products of the link reaction?

  Acetyl CoA, carbon dioxide (CO2), and reduced NAD (NADH)
• What is the chemical equation for the link reaction?

  pyruvate + NAD + CoA → acetyl CoA + carbon dioxide + reduced NAD
• What is the role of coenzyme A in the link reaction?

  It helps an enzyme carry out its function but is not used in the reaction itself
• What does coenzyme A consist of?

  A nucleoside (ribose and adenine) and a vitamin
• How does coenzyme A interact with pyruvate in the link reaction?

  CoA binds to the acetyl group of pyruvate to form acetyl CoA
• What happens to acetyl CoA in the Krebs cycle?

  It supplies the acetyl group to continue aerobic respiration
• What is the significance of the link reaction in cellular respiration?

  • Links glycolysis to the Krebs cycle
  • Brings part of carbohydrates, lipids, or amino acids into respiration
  • Connects the initial stage of respiration in the cytoplasm to later stages in the mitochondria