BRAINCAKEThe Krebs Cycle
The Krebs cycle takes place in the mitochondrial matrix. It is a series of enzyme-controlled reactions that completely oxidises the acetyl groups from the link reaction.
The main steps:
1. Acetyl coenzyme A (2C) combines with oxaloacetate (4C) to form citrate (6C). Coenzyme A is released and reused in the link reaction.
2. Citrate is decarboxylated and dehydrogenated to form a 5-carbon compound, releasing CO2 and producing reduced NAD.
3. The 5-carbon compound is decarboxylated and dehydrogenated again, forming a 4-carbon compound, CO2 and reduced NAD.
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Key terms in this lesson
- mitochondrial matrix
- The fluid inside the inner mitochondrial membrane, containing the enzymes of the link reaction and Krebs cycle, coenzymes and mitochondrial DNA.
- fad
- A coenzyme (flavin adenine dinucleotide) that acts as a hydrogen acceptor at one step of the Krebs cycle, becoming reduced when it accepts hydrogen.
More in Cellular Respiration
- Sprint Athletes
- Anaerobic Respiration in Plants and Fungi
- Discovery of Glycolysis
- Aerobic Respiration: Summary
- The Link Reaction
- The Electron Transport Chain
- Chemiosmosis
- Net Gain of ATP
All 20 lessons in Cellular Respiration · All Edexcel A-level Biology topics