Krebs cycle

Definition

The Krebs cycle, also known as the citric acid cycle or TCA cycle, is a series of enzymatic reactions in the mitochondria that generates energy through the oxidation of acetyl-CoA. It is a key part of cellular respiration and plays a central role in the metabolic breakdown of carbohydrates.

5 Must Know Facts For Your Next Test

1. The Krebs cycle occurs in the mitochondrial matrix in eukaryotic cells.
2. Each turn of the Krebs cycle produces 3 NADH, 1 FADH2, and 1 GTP (or ATP), along with releasing 2 molecules of CO2.
3. Oxaloacetate is regenerated at the end of each turn of the cycle to combine with a new acetyl-CoA.
4. The enzymes involved in the Krebs cycle are highly conserved across different species indicating its fundamental role in metabolism.
5. Intermediates from the Krebs cycle are used in various biosynthetic pathways.

Review Questions

• Where does the Krebs cycle take place within eukaryotic cells?
• What are the main products generated from one turn of the Krebs cycle?
• How is oxaloacetate important for the continuity of the Krebs cycle?

Related terms

Glycolysis:

The process that breaks down glucose into pyruvate, generating small amounts of ATP and NADH.

Electron Transport Chain:

A series of protein complexes located in the inner mitochondrial membrane that produce ATP using electrons from NADH and FADH2.

Acetyl-CoA:

A molecule that conveys carbon atoms within cells for their oxidation via the Krebs cycle.