2. Aerobic versus anaerobic metabollsm (30 points),. a. Triose phosphate isomera
ID: 252987 • Letter: 2
Question
2. Aerobic versus anaerobic metabollsm (30 points),. a. Triose phosphate isomerase (TIM) catalyzes the conversion of DHAP to GAP Cells lacking TIM can stay alive, but only under aerobic conditions (in the presence of oxygen). Explain why (2-4 sentences). b. The "Pasteur effect," first observed by Louis Pasteur in the 1860s, describes the following phenomenon: A culture of E. coli bacteria, grown in the absence of oxygen, consumes large amounts of glucose and produces lactic acid. If this culture of bacteria is then supplied with oxygen, two observations are made: observation 1: production of lactic acid stops observation 2: the rate of glucose consumption decreases but the overall rate of cell growth remains constant i. provide an explanation for observation 1 (2-3 sentences) ii. provide an e for observation 2 (2-3 sentences).Explanation / Answer
A. Because lack of TIM will accumulate DHAP and become useless. Only GAP enter in to further reaction and
undergoes substrate level phosporylation and generate ATP. In anaerobic reaction glycolysis is not enetred into TCA cycle. So only substrate level phosporylation important to generate ATP.
Aerobic Glycolysis with no TIM it undergoes only one cycle og glycolysis
Investment phase = - 2ATP used
one NADH due to mutation of TIM = + 3 ATP generate
Substrate level phosphorylation = + 2 ATP
NET ATP = 2 ATP
Then pyruvate enter into TCA cycle
In anaerobic reaction
Investment phase = - 2ATP used
one NADH due to mutation of TIM = 0 ATP generate
Substrate level phosphorylation = + 2 ATP
NET ATP = 0 ATP
In anaerobic reaction Net ATP is 0. So no energy production and cell not survive.
B.I. Presence of oxygen it undergoes aerobic reaction mitochondria starts ETC the O2 accept electron and converted into H2O. So no need to produce lactic acid. The pyruvate enter into TCA cycle and generate lot of ATP molecules.
ii. Overall glucose consumption decrease because at low glucose level or one glucose molecule produce lot of ATP molecules upto 38 ATP molecule in aerobic conditon. In anerobic reaction one glucose produce net ATP is 2. Thats why in anaerobic reaction lot of glucose are needed to grow a bacteria compare to aerobic condition.
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