3. The Link Reaction - (Aerobic respiration only)

Where does the link reaction take place?

In the mitochondria

What are the reactants and products in the link reaction?

Reactant - pyruvate

Products - Acetyl coenzyme A

Describe the process of the link reaction

1. Pyruvate is decarboxylated. So one carbon atom is removed from pyruvate in the form of carbon dioxide.

2. At the same time, pyruvate is oxidised to form acetate.

3. NAD is reduced to form reduced NAD.

4. Acetate is then combines with coenzyme A (CoA) to form acetyl coenzyme A.

   • no acetate is produced in this reaction.

How many times does the link reaction occur per glucose molecule?

Two pyruvate molecules are made for every glucose molecule that enters glycolysis. This means the link reaction the the 3rd stage, the Krebs cycle, happen twice for every glucose molecule.

1. What are the products of the link reaction? - 3

2. Where does each go to?

• 2 acetyl coenzyme A - Krebs Cycle

• 2 carbon dioxide - Released as a waste product.

• 2 reduced NAD - Oxidative phosphorylation.