A 3-year old dog has never been able to tolerate much physical activity. A veterinarian discovers that the dog's mitochondria can use only fatty acids and amino acids for cellular respiration, and its muscle cells produce elevated levels of lactate. Which of the following statements best explains the dog's condition?

Question

Quizplus · Accepted Answer

The dog's condition, characterized by an inability to tolerate much physical activity, elevated lactate levels in muscle cells, and reliance on fatty acids and amino acids for cellular respiration, suggests a problem with pyruvate transport into the mitochondria. Pyruvate is a key product of glycolysis and is normally transported into the mitochondria to enter the citric acid cycle. If pyruvate cannot enter the mitochondria, it would be converted into lactate in the cytosol, explaining the elevated lactate levels. This condition also explains why the dog's mitochondria cannot use glucose for energy, as the block in pyruvate transport prevents glucose metabolism from proceeding beyond glycolysis.

A 3-Year Old Dog Has Never Been Able to Tolerate