Question

Anaerobic process that takes place after glycolysis is called as
A. TCA
B. Calvin cycle
C. Krebs cycle
D. Fermentation

Answer 1

Hint: Anaerobic glycolysis is the conversion of glucose to lactate when limited amounts of oxygen \[\left( {{O_2}} \right)\] are available. It 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.

Complete step by step answer:
Anaerobic glycolysis is thought to have been the primary means of energy production in earlier organisms before oxygen was at high concentration in the atmosphere and, thus would represent a more ancient form of energy production in cells. The anaerobic process that takes place after glycolysis is called fermentation. Pyruvate in anaerobic respiration can undergo two metabolic processes. 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. Lactate is converted to pyruvate by the enzyme lactate dehydrogenase. Ethanol fermentation: Yeast and other anaerobic microorganisms convert glucose to ethanol and carbon dioxide rather than pyruvate. Pyruvate is first converted to acetaldehyde by enzyme pyruvate decarboxylase in the presence of thiamine pyrophosphate and magnesium. Carbon-dioxide is released during this reaction. Acetaldehyde is then converted to ethanol by the enzyme alcohol dehydrogenase.
Hence, the correct answer is option (D).

Note: Lactate produced at sites with high rates of glycolysis and glycogenolysis can be travelled to adjacent or distant sites as well as heart or skeletal muscles where the lactate can be utilized as a gluconeogenic precursor or as a substrate for oxidation.