Krebs Cycle:How,where,when ?
The citric acid cycle
- Also known as the tricarboxylic acid cycle (TCA cycle), or the Krebs cycle.
- Operates under aerobic conditions only.
- In eukaryotic cells, the citric acid cycle occurs in the matrix of the mitochondrion.
- In prokaryotic cells, such as bacteria which lack mitochondria, the TCA reaction sequence is performed in the cytosol with the proton gradient for ATP production being across the cell's surface (plasma membrane) rather than the inner membrane of the mitochondrion.
- Oxidizes the two-carbon acetyl group in acetyl CoA to 2CO2.
- Produces reduced coenzymes NADH and FADH2 and one ATP directly.
What happens ?
In Citric Acid Cycle,
- An acetyl group bonds with oxaloacetate to form citrate.
- Two decarboxylations remove two carbons as 2CO2.
- Four oxidations provide hydrogen for 3NADH and one FADH2.
- A direct phosphorylation forms GTP (ATP).
Net Reaction of Citric Acid Cycle: