Question

Which one of the following metabolic intermediates is common to glycolysis, nucleotide synthesis, and glycogen synthesis?

• A. ( Citrate)
• B. ( Oxaloacetate)
• C. ( Glucose 6-phosphate)
• D. ( Glycerol 3-phosphate)

Hint:

Glucose 6-phosphate is a central metabolic intermediate connecting glycolysis, the pentose phosphate pathway, and glycogen synthesis.

Answer 1

The Correct Option is C

Step 1: Role of glucose 6-phosphate in glycolysis. Glucose 6-phosphate (G6P) is the first intermediate formed in glycolysis after glucose is phosphorylated by hexokinase or glucokinase.
Step 2: Role of glucose 6-phosphate in nucleotide synthesis. G6P enters the pentose phosphate pathway, where it produces ribose-5-phosphate, an essential precursor for nucleotide synthesis.
Step 3: Role of glucose 6-phosphate in glycogen synthesis. G6P is converted to glucose 1-phosphate by the enzyme phosphoglucomutase, which is then used for glycogen synthesis via UDP-glucose.
Step 4: Evaluating options. - (A) Citrate: Involved in the TCA cycle, not directly common to glycolysis, nucleotide synthesis, and glycogen synthesis. - (B) Oxaloacetate: Involved in the TCA cycle and gluconeogenesis, not directly in nucleotide or glycogen synthesis. - (C) Glucose 6-phosphate: Correct, as it is central to glycolysis, nucleotide synthesis, and glycogen synthesis. - (D) Glycerol 3-phosphate: Involved in lipid metabolism, not nucleotide or glycogen synthesis.
Conclusion. The correct answer is (C) Glucose 6-phosphate, as it serves as a metabolic intermediate common to glycolysis, nucleotide synthesis, and glycogen synthesis.