Question

Link between glycolysis, Krebs' cycle and $\beta$-oxidation of fatty acid or carbohydrate and fat metabolism is
(1) Acetyl CoA
(2) a compound formed by oxidative de-carboxylation
(3) a $2$-carbon compound
(4) oxaloacetic acid

• A. 1,2 and 3 are correct
• B. 1 and 2 are correct
• C. 2 and 4 are correct
• D. 1 and 3 are correct

Answer 1

Answer: (A)

Before entering the Krebs' cycle, pyruvic acid ( $3C$ compound formed by glycolysis) converts into acetyl $Co-A$ ($2C$ compound) by the process of oxidative decarboxylation as follows
$\underset{\text{3 carbon}}{\text{Pyruvic acid}} + Co - A + NAD \xrightarrow[{\text { Lipoic acid }}]{ TPP , Mg ^{2+}} $
$\underset{\text{(2Carbon)}}{\text{Acetyl}} Co - A + NADH _{2}+ CO _{2}$
This reaction is commonly called link reaction or Gateway step and acetyl $Co-A$ is called connecting link between glycolysis and Krebs cycle.