Muscle tissues make lactate from pyruvate to do which of the following?

• A. Speed up the rate of glycolysis
• B. Get rid of pyruvate produced by glycolysis
• C. Utilize the energy in pyruvate
• D. Produce additional CO₂
• E. Regenerate NAD⁺

Answer: (E)

Verified step by step guidance

1. Understand the context: During anaerobic respiration, muscle cells convert pyruvate into lactate when oxygen is scarce.
2. Recognize the role of NAD+: In glycolysis, NAD+ is reduced to NADH. For glycolysis to continue, NAD+ must be regenerated.
3. Identify the process: The conversion of pyruvate to lactate is catalyzed by lactate dehydrogenase, which oxidizes NADH back to NAD+.
4. Connect the dots: By regenerating NAD+, the cell can maintain glycolysis, allowing for continued ATP production under anaerobic conditions.
5. Conclude the purpose: The primary reason for converting pyruvate to lactate is to regenerate NAD+, not to produce additional CO2 or utilize energy in pyruvate.