Answer to Question #85997 in Biochemistry for Vijay Pant

Question

Differentiate between the following with the help of examples in each case.
(i) Convergent and Divergent nature of catabolism and anabolism respectively
(ii)Homolactic and Alcoholic fermentation

Answer 1

(1) Catabolism is a set of biochemical reactions in the body aimed at splitting complex compounds that are included in the organs and tissues as their structural elements (proteins, nucleic acids, phospholipids, etc.) or deposited in them in the form of storage material (fat, glycogen, and others). Catabolism is a convergent process that is associated with the formation of several common end products from various molecules. For example, the complete oxidation of glucose, fats and some amino acids leads to the production of water and carbon dioxide.

Anabolism is a set of chemical processes occurring in a living organism and aimed at the formation and renewal of the structural parts of cells and tissues due to the synthesis of complex molecules from simpler ones with energy expenditure. Anabolism is a divergent process associated with the formation of various compounds from a few types of molecules. For example, acetyl-CoA is used in the synthesis of ketone bodies, sterols, and fatty acids.

(2) Both types of fermentation start with glycolysis that results in the formation of two pyruvate molecules from one glucose molecule. However, in homolactic fermentation, the enzyme lactate dehydrogenase transforms pyruvate to lactate. The process is associated with the oxidation of NADH to NAD+. In alcoholic fermentation, pyruvate is converted to acetaldehyde during the process of decarboxylation. The process causes the release of carbon dioxide. Next, the acetaldehyde molecule is reduced to ethanol. The process is also associated with the oxidation of NADH to NAD+. Alcoholic fermentation is observed mostly in yeasts and other microorganisms whereas homolactic fermentation takes place in specific bacteria Lactobacillus, yeasts and muscle cells.