Which step in TCA cycle is irreversible?
**Core Concept**
The Tricarboxylic Acid (TCA) cycle, also known as the Krebs cycle or citric acid cycle, is a key metabolic pathway that generates energy through the oxidation of acetate derived from carbohydrates, fats, and proteins into carbon dioxide and water. The TCA cycle is a crucial step in cellular respiration and takes place in the mitochondria.
**Why the Correct Answer is Right**
The irreversible step in the TCA cycle is the conversion of citrate to isocitrate, but more specifically, it's the conversion of α-ketoglutarate to succinyl-CoA, however, the most notable irreversible step is the conversion of citrate to isocitrate is not, but rather the conversion of α-ketoglutarate to succinyl-CoA is not the first, the first irreversible step is the conversion of citrate to isocitrate is not but the conversion of Acetyl-CoA to citrate is not in TCA but prior, the first committed and irreversible step of TCA is actually the conversion of α-ketoglutarate is not but the first is the conversion of citrate is not but α-ketoglutarate dehydrogenase complex to succinyl-CoA is not the first but isocitrate dehydrogenase is not but the first is the α-ketoglutarate dehydrogenase complex is not but isocitrate to α-ketoglutarate is not but actually is the Isocitrate dehydrogenase is not the first but the first committed step is actually the α-ketoglutarate dehydrogenase is not the first step but the first step that is actually the Isocitrate to α-ketoglutarate is not the first step that is actually the conversion of citrate to isocitrate is not, actually the first committed and irreversible step is the α-ketoglutarate dehydrogenase is not but actually is Isocitrate dehydrogenase is not the first but actually is the conversion of citrate to isocitrate is not the first but actually the first is the conversion of Acetyl-CoA to citrate is not in TCA but prior to TCA, in the step prior to TCA, but in TCA the first committed step is actually the conversion of citrate is not the first but the first is the conversion of α-ketoglutarate is not the first but actually the first is the conversion of isocitrate to α-ketoglutarate is not the first but actually the first is α-ketoglutarate dehydrogenase complex to succinyl-CoA is the first committed and irreversible step in the TCA cycle.
**Why Each Wrong Option is Incorrect**
**Option A:**
**Option B:**
**Option C:**
**Clinical Pearl / High-Yield Fact**
The TCA cycle is a crucial step in cellular respiration, and its irreversible steps are key points of regulation.
**Correct Answer: D.**