question_answer

Directions : (21 - 25)

Read the passage given below and answer the following questions.

We have so far seen the effect of a gene on a single phenotype or trait. There are however instances where a single gene can exhibit multiple phenotypic expression. Such a gene is called a pleiotropic gene. The underlying mechanism of pleiotropy in most cases is the effect of a gene on metabolic pathways which contributes towards different phenotypes. An example of this is the disease phenylketonuria (PKU; Foiling, 1934) which occurs in humans. The disease is caused by mutation in the gene that codes for the enzyme phenyl alanine hydroxylase i.e., single gene mutation. Pleiotropism is defined as a phenomenon when single gene may produce more than one effect i.e., the multiple effect of a gene or control several phenotypes depending on its position. This results in a phenotypic expression characterized by mental retardation and a reduction in hair and skin pigmentation (albinism). In Drosophila white eye mutation leads to depigmentation in many other parts of the body, giving a pleiotropic effect. In transgenic organisms, the introduced gene can produce different effects depending on where the gene has introgressed.

Single gene is controlling multiple phenotypic expression is referred as

A) Monogene

B) Polygenes

C) Pleiotropic

D) Digenes