Question

List out briefly the certain characteristics of the Quantitative inheritance.

Answer 1

Characteristics of Quantitativbe Genetics:

The quantitative inheritance have the following characteristics:

1. The segregation phenomenon occurs at an indefinitely large number of gene loci.

2. If a substitution of a allele occurs in a gene locus then such allelic substitutions have trivial effects.

3. The genes for a multiple trait have different biochemical functions but similar phenotypic effects, therefore, the phenotypic eflects of gene substitutions are interchangeable.

4. Blocks of genes are bound together by inversions and transmitted as units from inversion heterozygotes to their progeny, but such blocks are broken up by crossing over in insersion homozygotes.

5. The polygenes have pleiotropic effects; that is, one gene may modify or suppress more than one phenotypic trait. A single allele may do only one thing chemically but may ultimately affe many characters.

6. The environmental conditions have considerable effect en the phenotypic expression of polygenes for the quantitative traits. For example, height in many plants (e.g., corn, tomato, pea, marigold) is genetically controlled quantitative trait, but some environmental factors as soil, fertility, texture, and water, the tempera- ture, the duration and wavelength of incident light, the occurrence of parasites, etc., also affect the height. Similarly, identical twins with identical genotypes, if grow up in different kinds of environments, show different intelligence quotients.

Quantitative genetics:

It deals with the phenotypes which vary continuously as opposed to discretely identifiable phenotypes and gene products.