The connecting link between glycolysis and Krebs cycle is

Explanation

(1) Glycolysis is connected to Krebs cycle by a link reaction called acetylation.
(2) Pyruvic acid or pyruvate formed during glycolysis undergoes oxidative decarboxylation before entering the Krebs cycle.
(3) This reaction is catalysed by the enzyme pyruvic dehydrogenase. The coenzyme NAD and the coenzyme A are required for this reaction.
(4) Pyruvic acid (pyruvate) undergoes decarboxylation followed by oxidation in which the `H_(2)` which is removed is taken up by NAO leading to the formation of `NADH_(2)`
(5) The acetyl fraction (2C) which remains after decarboxylation is taken up by the coenzyme A resulting in the formation of acetyl Co-A. This reaction is known as acetylation of pyruvate.
(6) Glycolysis terminates with the formation of pyruvate and food enters the Krebs cycle in the form of acetyl Co-A. Therefore acetylatlon of pyruvate or formation of acetyl Co-A is known as connecting link between glycolysis and Krebs cycle or link reaction.
(7) The link reaction can be summarized as follows: