In a typical eukaryotic cell, where does the Krebs (citric acid) cycle primarily occur?

• A. In the mitochondrial matrix
• B. In the nucleus
• C. On the inner mitochondrial membrane
• D. In the cytosol

Answer: (A)

Verified step by step guidance

1. Recall that the Krebs cycle, also known as the citric acid cycle, is a key metabolic pathway involved in cellular respiration, where acetyl-CoA is oxidized to produce energy carriers like NADH and FADH2.
2. Understand that in eukaryotic cells, cellular respiration is compartmentalized, with different stages occurring in specific locations: glycolysis in the cytosol, the Krebs cycle in the mitochondria, and the electron transport chain on the inner mitochondrial membrane.
3. Identify that the Krebs cycle specifically takes place in the mitochondrial matrix, which is the innermost compartment of the mitochondrion, where the enzymes for the cycle are located.
4. Note that the inner mitochondrial membrane hosts the electron transport chain and ATP synthase, not the Krebs cycle itself.
5. Conclude that among the given options, the correct location for the Krebs cycle is the mitochondrial matrix.