Where does the Citric Acid Cycle take place?

Where does the Citric Acid Cycle take place?

• A. Cytoplasm
• B. Intermembrane space
• C. Matrix of the Mitochondria
• D. Chloroplast stroma

Answer: (C)

The main idea here is that where a metabolic pathway happens is determined by the cellular compartment that houses its necessary enzymes and substrates. The Citric Acid Cycle takes place in the mitochondrial matrix because that's where the soluble enzymes of the cycle reside and where the acetyl-CoA produced from pyruvate oxidation is delivered. In the matrix, the cycle oxidizes acetyl-CoA to CO2 and generates NADH and FADH2 to fuel the electron transport chain. The inner mitochondrial membrane houses the electron transport chain itself, while the intermembrane space mainly stores the proton gradient built up for ATP synthesis. Cytoplasm is where glycolysis occurs, and chloroplast stroma is the site of photosynthetic reactions in plants. In prokaryotes, without mitochondria, the cycle runs in the cytoplasm. So, the Citric Acid Cycle occurs in the matrix of the mitochondria.

The main idea here is that where a metabolic pathway happens is determined by the cellular compartment that houses its necessary enzymes and substrates. The Citric Acid Cycle takes place in the mitochondrial matrix because that's where the soluble enzymes of the cycle reside and where the acetyl-CoA produced from pyruvate oxidation is delivered. In the matrix, the cycle oxidizes acetyl-CoA to CO2 and generates NADH and FADH2 to fuel the electron transport chain. The inner mitochondrial membrane houses the electron transport chain itself, while the intermembrane space mainly stores the proton gradient built up for ATP synthesis. Cytoplasm is where glycolysis occurs, and chloroplast stroma is the site of photosynthetic reactions in plants. In prokaryotes, without mitochondria, the cycle runs in the cytoplasm. So, the Citric Acid Cycle occurs in the matrix of the mitochondria.