Question

How many dehydrogenation reactions in Krebs cycle?

Hint:

Remember that the dehydrogenation reactions in the Krebs cycle are critical for generating NADH and FADH2, which are used in the electron transport chain to produce ATP.

Answer 1

There are 4 dehydrogenation reactions in the Krebs cycle (also known as the citric acid cycle or TCA cycle).

Explanation:

• Dehydrogenation reactions: These are reactions in which hydrogen atoms (usually in the form of electrons and protons) are removed from a molecule. In the Krebs cycle, dehydrogenation reactions are crucial for the transfer of electrons to electron carriers, NAD⁺ and FAD, which will be used in the electron transport chain for ATP production.

Specific dehydrogenation reactions in the Krebs cycle:

1. Isocitrate to α-Ketoglutarate: This reaction involves the dehydrogenation of isocitrate to form α-ketoglutarate, with the reduction of NAD⁺ to NADH and the release of a molecule of CO₂.
2. α-Ketoglutarate to Succinyl-CoA: α-Ketoglutarate undergoes dehydrogenation and decarboxylation, forming succinyl-CoA. In this step, NAD⁺ is reduced to NADH, and CO₂ is released.
3. Succinate to Fumarate: Succinate is oxidized to fumarate by the enzyme succinate dehydrogenase. In this reaction, FAD is reduced to FADH₂.
4. Malate to Oxaloacetate: Malate is oxidized to oxaloacetate, with NAD⁺ being reduced to NADH.

Role of NADH and FADH₂: The NADH and FADH₂ produced during these dehydrogenation steps carry high-energy electrons to the electron transport chain, where they contribute to the generation of ATP, the energy currency of the cell.

In total, the Krebs cycle contains 4 dehydrogenation reactions, each contributing to energy production in aerobic respiration.