AP BIOLOGY

Detailed explanation-1: -Pyruvate can be formed in the cytosol by glycolysis, or conversion from alanine by ALT, from lactate by LDH-B or from malate by malic enzyme (ME). Pyruvate crosses the outer mitochondrial membrane (OMM) probably via the VDAC into the intermembrane space (IMS). Pyruvate is then transported across the IMM by the MPC.

Detailed explanation-2: -Pyruvic acid is transported into the mitochondria via a monocarboxylic acid cotransporter and is then metabolized by PDH into acetyl-CoA. Metabolism of acetyl-CoA follows the pathway described previously.

Detailed explanation-3: -Pyruvate is produced in the cytoplasm and is then transported into the mitochondria, where it is converted to acetyl-CoA; acetyl-CoA subsequently reacts with oxaloacetate to form citrate, thus entering the tricarboxylic acid (TCA) cycle.

Detailed explanation-4: -Pyruvate, the end product of glycolysis, plays a major role in cell metabolism. Produced in the cytosol, it is oxidized in the mitochondria where it fuels the citric acid cycle and boosts oxidative phosphorylation.

Detailed explanation-5: -Pyruvate is actively transported into the mitochondrion through MPC. TcMPC is a heterooligomer composed of two small integral membrane proteins, TcMPC1 and TcMPC2, which have two and three predicted transmembrane domains, respectively. In the mitochondrion of control cells (top), pyruvate import is inhibited by UK5099.