Question

Name the connecting link between glycolysis and TCA cycle and explain it.

Answer 1

Hint:
The connecting link will be formed when the end product of glycolysis will get converted into the start product of TCA cycle.

Complete answer:
First of all you should know what glycolysis and TCA cycle to understand this question. Glycolysis is a process or metabolic pathway where there is formation of pyruvate from glucose and the energy is released in this process in the form of ATP and NADH. The final or the end product of glycolysis is pyruvate.
 TCA cycle is also known as krebs cycle. It is an important part of aerobic respiration and it is the main source of energy for cells. The TCA cycle requires Acetyl CoA to start. Acetyl in Acetyl CoA means the acetyl group and CoA means Coenzyme A.
So the connecting link will be provided by that reaction which will convert the end product of glycolysis into the starting product of the TCA cycle which is done by the Link reaction in the mitochondrial matrix. So the glycolysis is followed by a link reaction which makes a connecting link between the TCA cycle and glycolysis. In other words, you can say link reaction provides a link between the TCA and glycolysis. This link reaction is then followed by a TCA cycle which occurs inside the mitochondria.
Now the link reaction leads to the conversion of pyruvate which is 3 carbon molecules into acetyl CoA which is 2 carbon molecules. This reaction results in decarboxylation of pyruvic acid The Acetyl CoA thus formed further enters the TCA cycle.

Thus, the connecting link between glycolysis and TCA cycle is Acetyl CoA.

Note: In the link reaction, pyruvate gets converted into acetyl CoA and the enzyme used in this reaction is pyruvate dehydrogenase complex. The connecting link is Acetyl CoA which further goes for the Krebs cycle to start the series of reactions in Krebs cycle.