A suspension of yeast supplied with glucose as its source of energy was transferred from an aerobic environment to an anaerobic one.Which result would you predict for the rate of glucose utilization and the rate of ethanol production after the transfer? Assume that the yeast must expend the same amount of energy to survive in both environments.

Question

Quizplus · Accepted Answer

When yeast is transferred from an aerobic to an anaerobic environment, it switches from aerobic respiration to alcoholic fermentation. This means that the yeast's primary method of generating ATP changes from oxidative phosphorylation to substrate-level phosphorylation. Since substrate-level phosphorylation generates less ATP than oxidative phosphorylation, the yeast must consume more glucose to generate the same amount of ATP as before. Therefore, the rate of glucose utilization would increase. On the other hand, alcoholic fermentation generates ethanol as a byproduct. Since the yeast is now generating energy through this pathway, the rate of ethanol production would increase as well. Therefore, both glucose usage and ethanol production would increase after the transfer.

A Suspension of Yeast Supplied with Glucose as Its Source