Question

What is the difference between anaerobic respiration in animals compared to anaerobic respiration in plants, yeast and bacteria?

Answer 1

Anaerobic respiration takes place without oxygen and there are two types of anaerobes present, one is facultative while the other is obligate. Only the yeast show facultative anaerobic respiration while the rest show obligate anaerobic respiration. Anaerobic respiration leads to incomplete oxidation of the respiratory substrate.

Complete answer:
Anaerobic respiration starts with glycolysis and further leads to an incomplete breakdown of pyruvate.
In animals, anaerobic respiration takes place in muscles where the pyruvic acid from glycolysis gets reduced to form lactic acids. In this process, carbon dioxide does not get produced and the reaction is catalysed by the enzyme lactic dehydrogenase which requires Flavin mononucleotide and zinc ion. After vigorous exercise lactic acid accumulates leading to muscular fatigue and in rest, this lactic acid gets reconnected into pyruvic acid and used up in aerobic respiration.
In plants, yeast and some bacteria, anaerobic respiration takes place where the pyruvate first undergo decarboxylation with the enzyme pyruvate decarboxylase, transacetylase, magnesium ion and thiamine pyrophosphate. This leads to the production of acetaldehyde and carbon dioxide from the pyruvic acid. Acetaldehyde by accepting hydrogen ions gets converted into alcohol. Accumulation of ethanol by fermentation in yeast leads to the death of the cell. In this anaerobic respiration does not occur indefinitely and produces toxic substances with little energy.

Note:
In the case of bacteria like lactic acid bacteria the process of anaerobic respiration is similar to that of animals where pyruvic acid gets converted into lactic acid. The glycolysis process occurs without oxygen and produces pyruvic acid, it is common in both anaerobic and aerobic respiration.