Question

During lactic acid fermentation, how many ATPs are lost when two molecules of pyruvic acid form two molecules of lactic acid?

• A. 1 ATP
• B. 3 ATPs
• C. 6 ATPs
• D. There is no loss of ATP

Answer 1

The correct option is C 6 ATPs

When one molecule of pyruvic acid is converted to one molecule of lactic acid in the presence of the enzyme, lactate dehydrogenase, one NADH gets converted to ${\mathrm{NAD}}^{+}$. Therefore, two molecules of NADH will be utilised in order to produce two molecules of ${\mathrm{NAD}}^{+}$when two molecules of pyruvic acid get converted to two molecules of lactic acid.
One molecule of NADH has the ability to produce three ATP molecules. Therefore, two molecules of NADH will be able to produce six molecules of ATP. Therefore, six ATP molecules are lost in the process of lactic acid fermentation.