According to Mendel, a genetical character is controlled by the combined action of two genes or factors in the same loci of two homologus chromosomes. It means that each gene has two alternative forms or
alleles and their expression are knwon as allelomorphs. Of these two, one is dominant and the other recessive. However, some genetical characters are determined by several forms of an allele known as multiple alleles. Examples for multiple allelism.
1. Coat colour in rabbits
Rabbits have five kinds of skin colour, coloured (agouti), chinchilla, himalayan albino and albino, light grey. Of these, the chinchilla variety is lighter in colour. Himalayan albino will have pink eyes, white coat colour and
black colour in tips like nose, tail and feet.
A crossing of a homozygous coloured rabbit with an albino resulted in following F1 and F2 generation.
In chinchilla, coat colour is lighter than the coloured (agouti). The coloured character is dominant over chinchilla. However F1 hybrids between chinchilla and himalayan albino (Cchch) or between chinchilla and albino (cchca) show light grey skin colour. The occurrence of light grey colour is due to partial expression of the gene for chinchilla in a heterozygous state.
alleles and their expression are knwon as allelomorphs. Of these two, one is dominant and the other recessive. However, some genetical characters are determined by several forms of an allele known as multiple alleles. Examples for multiple allelism.
1. Coat colour in rabbits
Rabbits have five kinds of skin colour, coloured (agouti), chinchilla, himalayan albino and albino, light grey. Of these, the chinchilla variety is lighter in colour. Himalayan albino will have pink eyes, white coat colour and
black colour in tips like nose, tail and feet.
A crossing of a homozygous coloured rabbit with an albino resulted in following F1 and F2 generation.
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