Question

Overall Glycolysis yields some ATPs, but in early stages, ATP is utilised to phosphorylate sugar substrates. In which of the following steps is ATP consumed?

• A. Sucrose to D-glucose catalysed by invertase
• B. Fructans to D-Fructose catalysed by β-fructofuranosidases
• C. Starch to glucose-1-phosphate catalysed by phosphorylase
• D. D-glucose to glucose-6-phosphate catalysed by hexokinase

Hint:

Remember that glycolysis involves two ATP-consuming steps: phosphorylation of glucose (hexokinase) and phosphorylation of fructose-6-phosphate (phosphofructokinase1).

Answer 1

The Correct Option is D

1. In the first step of glycolysis, hexokinase catalyzes the phosphorylation of D-glucose to glucose-6-phosphate using one molecule of ATP.
2. This phosphorylation step is critical for trapping glucose inside the cell and initiating glycolysis.
3. The other options involve either enzymatic cleavage or phosphorylation without ATP usage.