Question

The oxidation of malate to oxaloacetate is coupled to the reduction of NAD+ to NADH + H+. Here NAD+ is a ________?

1) coenzyme
2) substrate
3) enzyme
4) product

Answer 1

NAD+ is a coenzyme that assists the enzyme malate dehydrogenase in the reduction-oxidation reaction, where malate is oxidized to oxaloacetate and NAD+ is reduced to NADH + H+ in the citric acid cycle. Option 1

Step-by-step explanation:

The process being described is the final step of the citric acid cycle, where the oxidation of malate to oxaloacetate is coupled to the reduction of NAD+ to NADH + H+. The molecule NAD+ that accepts electrons during this reaction is known as a coenzyme.

This is because it assists the enzyme malate dehydrogenase in catalyzing the reaction. In this process, the enzyme facilitates the transfer of electrons and hydrogen from malate to NAD+, converting it to NADH, which is then used to help generate ATP via the electron transport chain. Hence, the correct answer is that NAD+ is a coenzyme. Option 1