AP BIOLOGY

Detailed explanation-1: -Pyruvate is produced by glycolysis in the cytoplasm, but pyruvate oxidation takes place in the mitochondrial matrix (in eukaryotes).

Detailed explanation-2: -Pyruvate dehydrogenase and carboxylase enzymes are localized to the mitochondrial matrix and, therefore, pyruvate must be transported from the cytosol through both the outer and the inner mitochondrial membranes.

Detailed explanation-3: -Pyruvate is synthesised in the cytosol by the process of glycolysis. For energy synthesis, pyruvate enters the mitochondria by active transport with the help of pyruvate translocase, a transport protein. Pyruvate is utilised in the citric acid cycle to produce acetyl CoA.

Detailed explanation-4: -In eukaryotic cells, the pyruvate molecules produced at the end of glycolysis are transported into the mitochondrial matrix (the middle region of the mitochondria) (Figure 1). In the mitochondrial matrix, pyruvate will be transformed into a two-carbon acetyl group by removing a molecule of carbon dioxide.

Detailed explanation-5: -In the matrix, pyruvic acid is converted to lactic acid before the Krebs cycle begins. 6. The compound that joins with a 4-carbon molecule in the Krebs cycle is called acetyl-CoA.