Identify the correct sequence of events in Kreb’s cycle.
Identify the correct sequence of events in Kreb’s cycle.
The correct option is B Acetyl CoA → Citric acid → α-ketoglutaric acid→ Succinic acid → Fumaric acid → Malic acid →OAA
Steps of Kreb cycle are:
Step 1: The first step is the condensation of acetyl CoA with 4-carbon compound oxaloacetate to form 6C citrate, coenzyme A is released. The reaction is catalysed by citrate synthase.
Step 2: Citrate is converted to its isomer, isocitrate. The enzyme aconitase catalyses this reaction.
Step 3: Isocitrate undergoes dehydrogenation and decarboxylation to form 5C 𝝰-ketoglutarate. A molecular form of CO2 is released. Isocitrate dehydrogenase catalyses the reaction. It is an NAD+ dependent enzyme. NAD+ is converted to NADH.
Step 4: 𝝰-ketoglutarate undergoes oxidative decarboxylation to form succinyl CoA, a 4C compound. The reaction is catalyzed by the 𝝰-ketoglutarate dehydrogenase enzyme complex. One molecule of CO2 is released and NAD+ is converted to NADH.
Step 5: Succinyl CoA forms succinate. The enzyme succinyl CoA synthetase catalyses the reaction. This is coupled with substrate-level phosphorylation of GDP to get GTP. GTP transfers its phosphate to ADP forming ATP.
Step 6: Succinate is oxidised by the enzyme succinate dehydrogenase to fumarate. In the process, FAD is converted to FADH2.
Step 7: Fumarate gets converted to malate by the addition of one H2O. The enzyme catalysing this reaction is fumarase.
Step 8: Malate is dehydrogenated to form oxaloacetate, which combines with another molecule of acetyl CoA and starts the new cycle. Hydrogens removed, get transferred to NAD+ forming NADH. Malate dehydrogenase catalyses the reaction.
Steps of Kreb cycle are:
Step 1: The first step is the condensation of acetyl CoA with 4-carbon compound oxaloacetate to form 6C citrate, coenzyme A is released. The reaction is catalysed by citrate synthase.
Step 2: Citrate is converted to its isomer, isocitrate. The enzyme aconitase catalyses this reaction.
Step 3: Isocitrate undergoes dehydrogenation and decarboxylation to form 5C 𝝰-ketoglutarate. A molecular form of CO2 is released. Isocitrate dehydrogenase catalyses the reaction. It is an NAD+ dependent enzyme. NAD+ is converted to NADH.
Step 4: 𝝰-ketoglutarate undergoes oxidative decarboxylation to form succinyl CoA, a 4C compound. The reaction is catalyzed by the 𝝰-ketoglutarate dehydrogenase enzyme complex. One molecule of CO2 is released and NAD+ is converted to NADH.
Step 5: Succinyl CoA forms succinate. The enzyme succinyl CoA synthetase catalyses the reaction. This is coupled with substrate-level phosphorylation of GDP to get GTP. GTP transfers its phosphate to ADP forming ATP.
Step 6: Succinate is oxidised by the enzyme succinate dehydrogenase to fumarate. In the process, FAD is converted to FADH2.
Step 7: Fumarate gets converted to malate by the addition of one H2O. The enzyme catalysing this reaction is fumarase.
Step 8: Malate is dehydrogenated to form oxaloacetate, which combines with another molecule of acetyl CoA and starts the new cycle. Hydrogens removed, get transferred to NAD+ forming NADH. Malate dehydrogenase catalyses the reaction.
