In which part of the mitochondria does the Krebs cycle occur?

The Krebs cycle, also known as the citric acid cycle or TCA cycle, occurs in the mitochondrial matrix. This is the fluid-filled space within the inner membrane of the mitochondria, where enzymes and reactants are present to facilitate the various chemical reactions involved in the cycle.

During the Krebs cycle, acetyl-CoA is oxidized to produce carbon dioxide, ATP, and high-energy electron carriers like NADH and FADH2, which are essential for the electron transport chain that follows. The specific environment of the mitochondrial matrix is ideal for these enzymatic reactions due to the concentration of necessary substrates and the presence of specific enzymes that catalyze the reactions.

In contrast, the inner mitochondrial membrane and outer mitochondrial membrane serve different functions related to electron transport and the regulation of substances entering and leaving the mitochondrion, respectively, while the cytoplasm is where glycolysis occurs, and not where the Krebs cycle takes place.