Question

82. Define the following:
(i) Pleiotropy
(ii) Polygenes
(iii) Allelic interaction​

Answer 1

Answer:                                                                                                                              

i) Pleiotropy occurs when one gene will code and control the phenotype or expression of several different and unrelated traits. Pleiotropy is most often a bad thing, as many diseases are due to a gene controlling so many traits at once. For example, phenylketonuria is a disease caused by pleiotropy.

ii)  any of a group of nonallelic genes that collectively control the inheritance of a quantitative character or modify the expression of a qualitative character

iii) Gene interaction is the influence of allelic or non-allelic genes on normal phenotypic expression of the trait. In other words, cases where two genes of the same allelic pair or genes of two or more different allelic pairs influence one another is called gene interaction.