Look at the eight steps of the citric acid cycle (Figure 21.8) and answer the following questions:


a. Which steps involve oxidation reactions?

Verified step by step guidance

1. Step 1: Review the citric acid cycle (also known as the Krebs cycle or TCA cycle) to identify the steps involved. The cycle consists of eight main steps, each catalyzed by a specific enzyme.
2. Step 2: Understand that oxidation reactions in the citric acid cycle involve the removal of electrons from a substrate, often accompanied by the reduction of NAD+ to NADH or FAD to FADH2.
3. Step 3: Identify the specific steps in the citric acid cycle where NAD+ is reduced to NADH. These steps typically involve the oxidation of a substrate.
4. Step 4: Identify the step in the citric acid cycle where FAD is reduced to FADH2, which also indicates an oxidation reaction.
5. Step 5: List the steps identified in Steps 3 and 4 as the ones involving oxidation reactions in the citric acid cycle.

Key Concepts

Citric Acid Cycle

The citric acid cycle, also known as the Krebs cycle, is a series of enzymatic reactions that occur in the mitochondria, playing a crucial role in cellular respiration. It involves the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins, leading to the production of energy carriers like NADH and FADH2, which are essential for ATP synthesis.

Oxidation Reactions

Oxidation reactions involve the loss of electrons from a molecule, often accompanied by the addition of oxygen or the removal of hydrogen. In the context of the citric acid cycle, these reactions are critical for energy production, as they facilitate the conversion of substrates into energy-rich molecules, contributing to the overall metabolic pathway.

Enzymatic Steps

The citric acid cycle consists of eight distinct enzymatic steps, each catalyzed by specific enzymes that facilitate the conversion of substrates through various chemical transformations. Understanding which steps involve oxidation is essential for grasping how energy is extracted from organic molecules and how metabolic pathways are interconnected.