Question

A young animal has never had much energy. He is brought to a veterinarian for help and is sent to the animal hospital for some tests. There they discover his mitochondria can use only fatty acids and amino acids for respiration, and his cells produce more lactate than normal. Of the following, which is the best explanation of his condition?a. His cells contain something that inhibits oxygen use in his mitochondria.
b. His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane.
c. His cells cannot move NADH from glycolysis into the mitochondria.
d. His cells have a defective electron transport chain, so glucose goes to lactate instead of to acetyl CoA.
e. His cells lack the enzyme in glycolysis that forms pyruvate.

Answer 1

Answer:

b. His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane.

Explanation:

The formation of pyruvate from glucose occurs during the process of glycolysis. It occurs in the cytoplasm. Pyruvate must enter into the mitochondria so that it is decarboxylated into acetyl CoA to enter into the citric acid cycle. Following this, NADH and FADH2 formed during glycolysis and citric acid cycle are oxidized by electron transport chain and the resultant proton concentration gradient drives ATP synthesis.

The given animal lacks the protein that transports pyruvate across the outer mitochondrial membrane. Therefore, pyruvate can not enter into the citric acid cycle and the animal can not derive energy by aerobic respiration of glucose.