Chapter 13, Problem 13.40EP

Interpretation Introduction

Interpretation: To identify the two methods by which the supply of ${\text{NAD}}^{+}$ needed for Step 6 of glycolysis can be replenished.

Concept introduction: In the glycolysis metabolic pathway, a glucose molecule breaks down into two pyruvate molecules. Two ATP molecules NADH coenzymes are formed along with pyruvate in the glycolysis process. The net overall equation for the glycolysis process is as follows:

$\text{Glucose}+2\text{ADP}+2{\text{P}}_i+2{\text{NAD}}^{+}\to 2\text{pyruvate}+2\text{NADH}+2\text{ATP}+2{\text{H}}^{+}+2{\text{H}}_2\text{O}$

Lactate dehydrogenase enzymes convert pyruvate to lactate under anaerobic conditions in the human body. This anaerobic reduction of pyruvate to form lactate by enzymes is called lactate fermentation.