Question

In the muscle, when are glycolysis and the citric acid cycle both active and when are they both turned off?(2 points) When is only glycolysis active and when is only the citric acid cycle active?(2 points) Why? (2 points)

Answer 1

In the muscle, when are glycolysis and the citric acid cycle both active and when are they both turned off?

When we do normal physical work, both glycolysis and the citric acid cycle would be active in the muscle.

Both glycolysis and the citric acid cycle would be turned off in the muscle under hyperglycemic conditions (excess glucose in blood). This promotes glycogenesis from glucose not glucose breakdown.

When is only glycolysis active and when is only the citric acid cycle active? Why?

During strenuous exercise, only glycolysis is active. This is because, while doing strenuous exercise, oxygen supply to the muscles would be very low. This favors anaerobic glycolysis (no TCA cycle).

Under hypoglycemic or starvation conditions, only TCA cycle would occur. This is because under these conditions, energy is produced from fatty acids and proteins via TCA cycle, as there is no or less glucose available.