The phenomenon of pleiotropism refers to:

The phenomenon of pleiotropism refers to:
  1. More than two genes affecting a single character.
  2. Presence of several alleles of a single gene controlling a single crossover.
  3. Presence of two alleles, each of the two genes controlling a single trait.
  4. A single gene affecting multiple phenotypic expressions.

Solution

A single gene can exhibit multiple phenotypic expression in an organism. Such a gene is called a pleiotropic gene. The underlying mechanism of the pleiotropy is the effect of a gene (and its alleles) on the metabolic pathways which contribute towards different phenotypes.

Some common example of pleiotropy is phenylketonuria, a disease is caused by mutation in the gene that codes for the enzyme phenyl alanine hydroxylase (single gene mutation). This results into the phenotypic expression characterised by mental retardation and a reduction in hair and skin  pigmentation.

Asked in: NEET 2023 (All India)

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