Final answer:
Under anaerobic conditions, ATP production is limited to those generated by glycolysis. The net yield of ATP in this mutant yeast is two ATP molecules.
Step-by-step explanation:
Under anaerobic conditions, ATP production is limited to those generated by glycolysis. While a total of four ATPs are produced by glycolysis, two are needed to begin glycolysis, so there is a net yield of two ATP molecules.
Under anaerobic conditions, cells rely on glycolysis as the primary pathway for ATP production. Unlike aerobic respiration, where oxygen is available for the complete oxidation of glucose, anaerobic conditions force cells to generate ATP through glycolysis alone. Glycolysis is a series of enzymatic reactions that break down glucose into pyruvate, producing a small amount of ATP in the process.
In the context of anaerobic metabolism, glycolysis yields a net gain of two ATP molecules. However, it's important to note that the initial steps of glycolysis consume two ATP molecules for the phosphorylation of glucose. This results in a net production of two ATP molecules per glucose molecule. The limited ATP yield under anaerobic conditions reflects the absence of subsequent processes like the Krebs cycle and oxidative phosphorylation, which contribute significantly to ATP production in aerobic respiration.
This adaptation allows cells to sustain basic energy needs when oxygen is unavailable, although the overall efficiency is lower compared to aerobic metabolism. Anaerobic glycolysis is a vital mechanism, especially in situations where rapid ATP production is essential, such as during intense exercise or in environments with low oxygen availability.