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The Link Reaction

Biology: AQA A Level, topic 5.2.4

The Link Reaction

Pyruvate can be used in aerobic respiration by converting it to acetyl coenzyme A. This process is called the link reaction and it takes place in the matrix of the mitochondria.

Decarboxylation

Decarboxylation

  • Pyruvate is first actively transported from the cytoplasm across the mitochondrial membrane and into the matrix of the mitochondria.
  • In the mitochondrial matrix, pyruvate is decarboxylated and dehydrogenated to acetate, which is a two-carbon molecule.
  • CO2 is produced as a by-product.
  • NAD is reduced to NADH.
Coenzyme A

Coenzyme A

  • Acetate then combines with coenzyme A (CoA) to produce acetyl coenzyme A.
  • Acetyl coenzyme A is used in the Krebs cycle (the next stage of aerobic respiration).
  • The link reaction links glycolysis to the Krebs cycle.
Net gain

Net gain

  • The net gain from the link reaction is:
  • 1 CO2 molecule.
  • 1 NADH molecule.

Test yourself on The Link Reaction

  • Where does the link reaction take place?

  • Which of the following statements about the link reaction are true?

  • What is the name of the reaction that happens after glycolysis and before the Krebs cycle in aerobic respiration?

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