Question

Glyceraldehyde-3-phosphate dehydrogenase catalyzes the phosphorylation of glyceraldehyde-3-phosphate, but unlike other glycolytic reactions, it does not require energy investment from ATP. This reaction occurs in two stages: oxidation/reduction and phosphorylation.
Why is the oxidation/reduction reaction necessary to make phosphorylation favorable?

A. The oxidation/reduction reaction is necessary to oxidize phosphate, allowing addition to the substrate.B. The oxidation/reduction reaction is necessary to form an intermediate with a large free energy of hydrolysis.C. The oxidation/reduction reaction is necessary to produce NADH, which is required for ATP synthesis.D. The oxidation/reduction reaction is for the substrate to bind to the enzyme.

Answer 1

Answer:

Answer: The correct option is C

Explanation:

The glycolytic pathway involves the oxidation of glyceraldehyde 3-phosphate.

Glyceraldehyde 3-Phosphate is oxidized by NAD+ and an inorganic phosphate is incorporated into the product to form an acyl-phosphate, 1,3-bisphosglycerate, which is an energy rich intermediate. NAD+ is reduced by the transfer of an hydride ion to form NADH. Once NADH is formed, its affinity for the enzyme decreases so that the free NAD+ displaces this NADH. The energy released by the oxidation of the substrate is conserved in the terminal phosphoanhydride bond of ATP via the formation of high energy intermediates.

Thus the oxidation/reduction is necessary to produce NADP which is required for ATP synthesis.

Answer 2

Answer:B. The oxidation/reduction reaction is necessary to form an intermediate with a large free energy of hydrolysis

Explanation:

An oxidation-reduction reaction is catalyzed by glyceraldehyde 3-phosphate dehydrogenase, oxidation of aldehyde to a carboxylic acid by NAD + and the joining of 3-phosphophoglycerate a carboxylic acid and orthophosphate to form the acyl-phosphate 1,3-biphosphoglycerate. This is done together so that aldehyde oxidation can be used to drive the formation of acyl phosphate. Energy that is released in the oxidation of glyceraldehyde 3-phosphate to 3-phosphoglycerate is trapped temporarily as 1,3-bisphosphoglycerate the energy aids the transfer of phosphoryl group from 1,3-phosphoglycerate to ADP to yield ATP.