Question

Steps that produce NADH in the TCA cycle? (mnemonic)

Answer 1

In the TCA Cycle, NADH is produced in steps 3, 4, and 8, through the oxidation reactions catalyzed by isocitrate dehydrogenase, α-ketoglutarate dehydrogenase, and malate dehydrogenase, respectively.

Step-by-step explanation:

Steps That Produce NADH in the TCA Cycle:

The Tricarboxylic Acid (TCA) Cycle, also known as the Kreb's Cycle or Citric Acid Cycle, includes several steps that result in the production of the energy-carrying molecule NADH. Here are the specific steps within the cycle where NADH is produced:

1. In step 3, isocitrate is oxidized by isocitrate dehydrogenase to form α-ketoglutarate and CO₂, with the reduction of NAD+ to NADH.
2. The oxidation of α-ketoglutarate to succinyl-CoA by α-ketoglutarate dehydrogenase produces another molecule of NADH in step 4.
3. The final NADH is generated in step 8 when malate is oxidized to oxaloacetate by malate dehydrogenase.

A mnemonic to remember these steps is: "Is Citrate A Silly Silly Malate?" where the first letters of each word represent Isocitrate, Citrate, α-Ketoglutarate, Succinyl-CoA, Succinate, and Malate, with the steps producing NADH (Isocitrate, α-Ketoglutarate, Malate) highlighted.