Final answer:
Water is produced as a byproduct in the 9th step of glycolysis during the dehydration of 2-phosphoglycerate to form phosphoenolpyruvate, catalyzed by the enzyme enolase.
The correct answer is (D) step 9.
Step-by-step explanation:
In the enzymatic pathway of glycolysis, water is produced as a byproduct at a specific step. At this stage of the pathway, the enzyme involved is enolase, which acts on 2-phosphoglycerate (2-PG), removing a molecule of water to form phosphoenolpyruvate (PEP). This step is known as a dehydration reaction because it results in the elimination of water (H₂O).
The glycolysis pathway consists of several steps where different enzymes catalyze the conversion of glucose into pyruvate. Steps 1, 3, and 10 are regulated and involve ATP hydrolysis or generation, but water production specifically occurs at step 9. In addition to water being a byproduct, this step is critical for the pathway as it sets the stage for subsequent ATP generation.
To review, glycolysis begins with glucose, a six-carbon molecule, which is converted through a series of reactions into two three-carbon molecules of pyruvate. During this process, ATP is consumed in the early stages and then produced in the latter stages. The regulation of glycolysis primarily occurs at steps where ATP is either used or generated, but water production, as seen in step 9, is an example of a reaction that is not focused on energy currency but is still essential to the pathway's progress.
Among the options provided (A) 3, (B) 5, (C) 6, (D) 9, (E) 10, the correct answer is (D) step 9.