Question

Out of 38 ATP molecules produced per glucose, 32 ATP molecules are formed from NADH/FADH in

• A. respiratory chain
• B. Kreb's cycle
• C. oxidative decarboxylation
• D. EMP.

Answer 1

The Correct Option is A

The question pertains to the biological process of ATP production during cellular respiration. Understanding the process of ATP production in cellular respiration is key to answering such questions effectively.

In cellular respiration, ATP is produced in various stages, primarily in the following:

1. Glycolysis (also known as the Embden-Meyerhof-Parnas (EMP) pathway): During glycolysis, 2 ATP molecules are produced per molecule of glucose.
2. Kreb's cycle (Citric Acid Cycle): This cycle produces 2 ATP (or equivalent GTP) molecules per glucose molecule.
3. Oxidative decarboxylation: This process does not produce ATP directly. Instead, it forms NADH and FADH₂, which are electron carriers.
4. Respiratory chain (Electron Transport Chain or ETC): This is where the majority of ATP is produced. NADH and FADH₂ donate electrons to the chain, leading to the production of ATP through oxidative phosphorylation.

Now, considering the question, "Out of 38 ATP molecules produced per glucose, 32 ATP molecules are formed from NADH/FADH in the":

The answer is respiratory chain. Here's why:

• In the respiratory chain, NADH contributes approximately 2.5 ATP molecules per NADH, and FADH₂ contributes approximately 1.5 ATP molecules per FADH₂. Since a typical complete oxidation of glucose yields 10 NADH and 2 FADH₂ molecules, the computation is as follows:
  • 10 \times 2.5 = 25 \, \text{ATP from NADH}
  • 2 \times 1.5 = 3 \, \text{ATP from FADH}_2
  • Hence, 25 + 3 = 32 \, \text{ATP molecules} produced by the respiratory chain.
• These computations align with the answer choice given: respiratory chain, while the other stages do not primarily account for 32 ATPs via oxidative phosphorylation.

Thus, the correct answer is accurately justified and matches the scientific understanding of cellular respiration and ATP synthesis.