The Link Reaction (AQA A Level Biology): Revision Note

When oxygen is available the pyruvate produced during glycolysis enters the mitochondria, where it is involved in the next stage of respiration

• Pyruvate moves across the double membrane of the mitochondria and into the mitochondrial matrix

The transport process occurs against a concentration gradient, and so is an example of active transport

• ATP is required

• A membrane transport protein is involved

In the mitochondrial matrix pyruvate takes part in the link reaction

The link reaction occurs between glycolysis and the Krebs cycle

During the link reaction:

• pyruvate is oxidised to acetate, producing reduced NAD and CO₂

• acetate combines with coenzyme A to produce acetyl coenzyme A (acetyl CoA)

Products of the link reaction include:

• Acetyl CoA

• Carbon dioxide

• Reduced NAD

Acetyl CoA and NADH enter the Krebs cycle, while carbon dioxide is released as a waste product