Which glycolysis enzyme might be affected in someone with a mutation who experiences fatigue and muscle pain during intense exercise due to reduced energy production?

Question

This question asks you to think about how a mutation in a glycolytic enzyme might lead to symptoms like fatigue and muscle pain, especially during intense physical activity. It invites you to connect enzyme function with energy production in muscles, particularly under conditions where oxygen might be limited. You’re being asked to identify which step in glycolysis could be disrupted in a way that would affect the body’s ability to produce enough ATP during high-demand situations.

Answer 1

During high-intensity exercise, like sprinting or weightlifting, the body often relies on anaerobic respiration because oxygen can't be delivered to the muscles quickly enough. In these conditions, cells depend on glycolysis to produce ATP, and to keep glycolysis running, they also rely on lactic acid fermentation to regenerate NAD⁺.

A key enzyme in this process is lactate dehydrogenase. It catalyzes the conversion of pyruvate (produced at the end of glycolysis) into lactate, while also converting NADH back into NAD⁺. If someone has a mutation that reduces the function of lactate dehydrogenase, their cells would struggle to regenerate NAD⁺ efficiently during anaerobic exercise. This would slow or stop glycolysis, leading to reduced ATP production, and as a result, they would experience fatigue and muscle pain during strenuous activity.