For the first five steps of glycolysis, the appropriate sequence of enzymes is: A. phosphofructokinase-1 (PFK-1). B. hexokinase / glucokinase. C. fructose bisphosphate aldolase. D. Phosphoglucoisomerase. E. triose phosphate isomerase (TPI). a. B, D, C, A, E b. D, B, A, C, E c. B, D, E, C, A d. B, C, D, E, A e. A, C, B, E, D

B, D, A, C, E

Explanation:

The first five steps of glycolysis are explained below:

Step - 1 : The food we eat contains glucose which is converted to glucose-6-phosphate in the presence of enzyme hexokinase / glucokinase. One ATP molecule is consumed in this step.

Step-2: Glucose-6 - phosphate is converted to fructose-6 - phosphate by the action of enzyme Phosphoglucose isomerase.

Step-3: Fructose-6 - phosphate is converted to fructose-1,6-biphosphate in the presence of enzyme phosphofructokinase-1 (PFK-1). One more ATP molecule is consumed in this step.

Step-4: Fructose 1,6-bisphosphate in the presence of fructose-bisphosphate aldolase is converted to D-glyceraldehyde 3-phosphate (GADP) and dihydroxyacetone phosphate (DHAP)

Step-5: Dihydroxyacetone phosphate (DHAP) in the presence of triosephosphate isomerase (TPI) is converted to D-glyceraldehyde 3-phosphate (GADP).

Hence, the order it follows is:

B. hexokinase / glucokinase

D. Phosphoglucoisomerase

A. Phosphofructokinase-1 (PFK-1)

C. fructose bisphosphate aldolase

E. triose phosphate isomerase (TPI)

The trend is : B, D, A, C, E