Question

In $TCA$ cycle, the conversion of succinyl $CoA$ to succinic acid needs

• A. $GDP+iP$
• B. $CoA+GTP+iP$
• C. Acetyl $CoA+GTP+iP$
• D. Acetyl $CoA+GDP+iP$

Answer 1

The correct option is A $GDP+iP$

Succinyl $CoA$ to succinic acid

Krebs’ cycle can be defined as a stepwise, oxidative and cyclic degradation of acetyl $CoA$ derived from the end product of glycolysis i.e., pyruvate.

It takes place in mitochondria. In one if the steps of Krebs’ cycle, the $CoA$ of succinyl $CoA$ is replaced by a phosphate group. The phosphate group in succinyl $CoA$ is transferred to $GDP$ to convert it into $GTP$.

In some cells, $GDP—$guanosine diphosphate$—$is used instead of $ADP$, forming $GTP—$guanosine triphosphate$—$as a product. The four-carbon molecule produced in this step is called succinate or succinic acid.

Final answer:

(A) $GDP+iP$