Question

Please select the CORRECT statements regarding the central metabolic pathways.

a) Glycolysis converts one 6-C molecule of glucose to two 3-C molecules of pyruvate.
b) Carbon from glycolysis enters the TCA cycle in the form of pyruvate.
c) Carbon from glycolysis enters the TCA cycle in the form of acetyl-CoA.
d) The pentose phosphate pathway yields ATP, precursor metabolites and reducing power.

Answer 1

The CORRECT statements regarding the central metabolic pathways are

a) Glycolysis converts one 6-C molecule of glucose to two 3-C molecules of pyruvate.

c) Carbon from glycolysis enters the TCA cycle in the form of acetyl-CoA.

Step-by-step explanation:

The correct statements are a) and c). Glycolysis indeed converts one 6-C molecule of glucose to two 3-C molecules of pyruvate. This process involves a series of enzymatic reactions, resulting in the formation of two molecules of pyruvate, each containing three carbon atoms.

Regarding the entry of carbon from glycolysis into the TCA cycle, it occurs in the form of acetyl-CoA, not pyruvate. After glycolysis, pyruvate undergoes decarboxylation to form acetyl-CoA, releasing carbon dioxide in the process. Acetyl-CoA then enters the TCA cycle, contributing to the generation of reducing equivalents and ATP.

The incorrect statements are b) and d). Carbon from glycolysis does not directly enter the TCA cycle in the form of pyruvate (option b). Instead, pyruvate is converted to acetyl-CoA before entering the TCA cycle. Additionally, the pentose phosphate pathway does not yield ATP; it produces NADPH (reducing power) and precursor metabolites for biosynthesis. Therefore, statement d) is incorrect.