Question

2a. What is the net yield of ATP from 1 glucose molecule metabolized anaerobically to lactate? b. Why is the end product of anaerobic glycolysis in cells lactate, rather than pyruvate?

Answer 1

2 (a)

Two ATP molecules are produced when 1 glucose molecule is converted into lactate anaerobically

Explaination: Anaerobic glycolysis is the transformation of glucose to lactate when limited amounts of oxygen (O₂) are available. Anaerobic glycolysis is only an effective means of energy production during short, intense exercise, providing energy for a period ranging from 10 seconds to 2 minutes. The anaerobic glycolysis (lactic acid) system is dominant from about 10–30 seconds during a maximal effort. It replenishes very quickly over this period and produces 2 ATP molecules per glucose molecule or about 5% of glucose's energy potential (38 ATP molecules). The speed at which ATP is produced is about 100 times that of oxidative phosphorylation.

(b) Pyruvate is the terminal electron acceptor in lactic acid fermentation. When sufficient oxygen is not present in the muscle cells for further oxidation of pyruvate and NADH produced in glycolysis, NAD+ is regenerated from NADH by reduction of pyruvate to lactate. Pyruvate is converted to lactate by the enzyme lactate dehydrogenase. The standard free energy change of the reaction is -25.1 kJ/mol.