When O2 is added to an anaerobic suspension of cells using g

When O2 is added to an anaerobic suspension of cells using glucose at a high rate, the rate of glucose consumption declines dramatically as the added O2 is consumed, and, the accumulation of lactate ceases. This is known as the Pasteur Effect.

(A) Why does the accumulation of lactate cease after O2 is added?

(B) Why does the presence of O2 decrease the rate of glucose consumption?

Solution

pasteur effect : an inhibiting effect of oxygen on fermentation process as fermentation is anaerobic.

a) when o2 is added to anaerobic suspension it allows bacteria to convert from anaerobic lactic acid fermentation to oxidative phosphorylation as a mechanism for reoxidizing NADH and making ATP. ATP synthesis is more efficient under aerobic conditionthus the amount of glucose needed will decrease , pasteur effect.

b) cells produce more ATP per glucose molecule when oxidized aerobically so rate ofglucose consumption decreases.

net gain in glycolysis is : 1 molecule of glucose =2 ATP