Question

3. Discuss fermentation: Name the two types of fermentation. Give the end products of each type. Summarize the net energy gain of each type. Give examples of cells which carry out each type.

Answer 1

A series of metabolic steps used to extract the energy from the organic molecules like glucose is called cellular respiration

Fermentation: The metabolic process by which the organic compounds like glucose degraded into products like alcohol or organic acids in the absence of oxygen is called fermentation.

There are two types of fermentation

1) Lactic acid Fermentation 2) Alcoholic Fermentation

Lactic acid fermentation: the pyruvate which is produced in glycolysis converted to lactic acid by the lactate dehydrogenase which results in the generation of two NAD+ molecules from the 2 NADH2. The NAD+ molecules produced further drive the glycolysis.

Pyruvate => lactic acid + 2 NAD+

Net energy gain: two NAD+ which drive glycolysis and produce 2 ATPs

In skeletal muscles, there is high demand for energy so it depends upon the anaerobic glycolysis. The skeletal muscles use the lactic acid fermentation for production of energy.

Alcoholic Fermentation: the pyruvate which is produced in glycolysis first converted to acetaldehyde by the pyruvate decarboxylase. The acetaldehyde next converted to ethanol by alcohol dehydrogenase, which results in the generation of two NAD+ molecules from the 2 NADH2.

Pyruvate => acetaldehyde => ethanol + 2 NAD+

Net energy gain: two NAD+ which drive glycolysis and produce 2 ATPs

Alcoholic Fermentation observed in yeast and protests