Oxidation of Pyruvate (College Board AP® Biology)

Oxidation of Pyruvate

• Pyruvate (from glycolysis) is transported from the cytosol into the mitochondria

• If oxygen is available, aerobic respiration will continue

• Movement of pyruvate across the double membrane of the mitochondria occurs by active transport

  • It requires a transport protein and a small amount of ATP

Entry of Pyruvate into the Mitochondrion Diagram

Pyruvate enters the mitochondrial matrix from the cytosol (cytoplasm) by active transport

• This stage links glycolysis to the Krebs cycle

• Pyruvate is oxidized and acetyl coenzyme A (acetyl CoA) is formed

• During the process,

  • Hydrogen and an electron removed from pyruvate (dehydrogenation) are used to reduce NAD+ to form NADH

  • Carbon dioxide is removed from pyruvate (decarboxylation)

  • CoenzymeA (CoA) is added to form acetyl CoA

• The products are then used as follows:

  • Acetyl CoA - is used in the Krebs cycle

  • Carbon dioxide (CO₂) - which is released as a waste product

  • NADH - provides electrons to drive the electron transport chain

Oxidation of Pyruvate Diagram

The first stage of pyruvate oxidation occurs in the mitochondrial matrix.
It dehydrogenates and decarboxylates the three-carbon pyruvate to produce the two-carbon acetyl CoA that can enter the Krebs Cycle.