Genetics
Epistasis due to recessive genes is called recessive epistasis. In mice albinism (white coat) is produced by a recessive gene aa. There is a different gene B which in the dominant state (BB and Bb) produces grey coat colour called agouti, and when recessive (bb) leads to black coat colour. The recessive gene for albinism [...]
In poultry white birds belong to two different varieties namely white leghorns or white wyandottes. Experiments reveal that the gene for white plumage of white leghorns is dominant over the gene for coloured plumage of coloured varieties. But the gene for white plumage of white wyandottes is recessive to the gene for coloured plumage of [...]
Due to the phenomenon of dominance a recessive allele remains obscure in the hybrid. But when two different genes which are not alleles, both affect the same character in such a way that the expression of one masks, inhibits or suppresses the expression of the other gene, it is called epistasis. The gene that suppresses [...]
In 1900 Bateson and his colleagues studied inheritance of comb shape in fowls. There are four types of combs in fowls: rose, pea, walnut and single. Bateson first performed a cross between rose and single. The Fx hens all had a rose comb, and on inbreeding gave rise to an F2 progeny of rose and [...]
A monohybrid cross between a red-flowered snapdragon (Antirrhinum majus) and a white flowered variety does not produce red or white flowered plants in Fl as expected from mendelism. Instead the flowers are pink, i.e. intermediate between the two parents. This is because neither red flower colour nor white is dominant, but each allele has its [...]
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