Question

How is 6-phosphogluconate formed from ribulose-5-phosphate?

1) By the action of the enzyme phosphogluconate dehydrogenase
2) By the action of the enzyme ribulose-5-phosphate isomerase
3) By the action of the enzyme ribulose-5-phosphate kinase
4) By the action of the enzyme 6-phosphogluconate dehydrogenase

Answer 1

In glycolysis, 6-phosphogluconate is not formed from ribulose-5-phosphate. It is formed in the pentose phosphate pathway by the action of the enzyme ribulose-5-phosphate 3-epimerase and converted back to ribulose-5-phosphate by the action of the enzyme phosphogluconate dehydrogenase.

Step-by-step explanation:

In glycolysis, 6-phosphogluconate is not formed from ribulose-5-phosphate. Instead, it is formed in the pentose phosphate pathway. The correct answer is option 4) By the action of the enzyme 6-phosphogluconate dehydrogenase. In this pathway, ribulose-5-phosphate is converted to 6-phosphogluconate by the enzyme ribulose-5-phosphate 3-epimerase. Then, 6-phosphogluconate is further converted to ribulose-5-phosphate by the enzyme phosphogluconate dehydrogenase.

In summary, 6-phosphogluconate is formed from ribulose-5-phosphate by the action of the enzyme ribulose-5-phosphate 3-epimerase, and then converted back to ribulose-5-phosphate by the action of the enzyme phosphogluconate dehydrogenase.