Question

What is approximate ATP yield per mole of glucose for E.coli growing aerobically and considering that all glucose is converted into energy of ATP? (10 points).

Answer 1

Ans: Aerobic Respiration occurs in 3 steps

• Glycolysis
• Kerbs Cycle
• Electron Transport Chain

Let us now see how much ATP is generated in each steps:-

Glycolysis- In glycolysis, glucose is broken down into 2 molecules of pyruvate. During this stage, 4 ATP is produced. But ,during the beginning of the process, conversion of glucose into pyruvate consumes 2 ATP, the Net Energy after Glycolysis is 2 ATP.

Kerbs Cycle - In this step the pyruvate molecules made during glycolysis is converted into acetyl CoA. For each kerbs cycle 1 ATP is released. Since, during glycolysis 2 pyruvate molecules are formed, the kerbs cycle is repeated, thus generating 2 ATP in this stage.

Electron Transport Chain - This is the final step which produces the maximum ATP. It is initiated by the NADH and molecules formed during the kerbs cycle. Out of these, which one is present at that time, converts the ADP into ATP. The number of ATP generated in this process depends on the number of NADH molecules available and generally yields 32 or 34 ATP.

Hence, the Net ATP generated after these 3 steps, is 2+2+(32 or 34) = 36 or 38 ATP

Thus, One Molecule of Glucose can yield total of 36 or 38 ATP during Aerobic Respiration in E coli.