Question

Oxidation of glyceraldehyde phosphate is accompanied by
A) Oxidation of NaD+
B) Substrate level phosphorylation
C) Reduction of NaD+
D) Oxidative phosphorylation

Answer 1

Hint: Glyceraldehyde phosphate is a chemical compound that functions as an intermediate in many key metabolic pathways in all species. The chemical formula is $C_3H_7O_6P$.

Complete Answer:
>This compound is an intermediate of photosynthesis and glycolysis and gluconeogenesis.
>In glycolysis, glyceraldehyde phosphate is formed during the early phase by fructose-1,6-bisphosphate breakdown by the action of the enzyme aldolase. ATP is used during this process to manufacture glyceraldehyde phosphate and dihydroxyacetone phosphate.
>Glyceraldehyde phosphate shall proceed to the next step of glycolysis. Its isomer, dihydroxyacetone phosphate, must first be converted to glyceraldehyde phosphate (through the enzyme phosphate isomerase) before progressing to the next step of glycolysis.
>Glyceraldehyde phosphate formed in the fourth stage of glycolysis undergoes phosphorylation and dehydrogenation and is converted to 1,3-diphosphoglyceric acid. Phosphorylation 3-phosphoglyceraldehyde combines with a phosphate group derived from inorganic phosphoric acid contained in cytosols produced by 1,3-diphosphoglyceric acid. In dehydrogenation, a pair of hydrogen atoms separate from 3-phosphoglyceraldehyde molecules.
>This separation releases a significant amount of energy which is retained in a newly formed phosphate bond of 1, 3 diphosphoglyceric acid, resulting in a high energy bond. Out of 2 hydrogen atoms isolated from 3-phosphoglyceric acid, one full hydrogen atom with one proton and one additional electron is collected by NAD+ which is reduced to NADH. The remaining one hydrogen proton is left free in the cytosol.
?NADH is a high-energy material that holds the remainder of the energy produced by the splitting of hydrogen atoms.

Hence option ‘C’ is the correct answer.

Note:Glyceraldehyde phosphate is also a by-product of tryptophan, the important amino acid, in the biosynthesis pathway. It also exists as a reactant in the thiamine biosynthesis pathway (vitamin b1), another material that can not be produced by the human body.