how many molecules of water are added during kreb cycle

During one turn of the Krebs cycle, also known as the citric acid cycle, three molecules of water are added. Here are the steps:

1. Acetyl CoA (2 carbons) combines with oxaloacetate (4 carbons) to form citrate (6 carbons). This step is facilitated by the enzyme citrate synthase and a molecule of water is consumed.

2. Citrate is then converted to its isomer, isocitrate, via cis-Aconitate in a reaction facilitated by the enzyme aconitase.

3. Isocitrate is then oxidized by the enzyme isocitrate dehydrogenase to form alpha-ketoglutarate (5 carbons), CO2 and NADH. This step does not involve water.

4. Alpha-ketoglutarate is then oxidized by the enzyme alpha-ketoglutarate dehydrogenase to form succinyl-CoA (4 carbons), CO2 and NADH. This step also does not involve water.

5. Succinyl-CoA is then converted to succinate by the enzyme succinyl-CoA synthetase. In this step, a molecule of water is consumed.

6. Succinate is then oxidized to fumarate by the enzyme succinate dehydrogenase. This step does not involve water.

7. Fumarate is then hydrated to malate by the enzyme fumarase. In this step, a molecule of water is added.

8. Finally, malate is oxidized to oxaloacetate by the enzyme malate dehydrogenase. This step does not involve water.

So, in total, three molecules of water are added during one turn of the Krebs cycle.