following the rediscovery of Mendel’s work in the early 1900s, research focused on many ways in which genes can influence an
individual’s phenotype. This course of investigation, stemming from Mendel’s findings, is called neo-Mendelian genetics or post-
Mendelian genetics. Hypotheses that modified and extended the Mendelian principles were proposed and tested with specifically
designed crosses.
usually a single gene controls one character and the alleles of a pair are related as dominant and recessive. but various exceptions
have been noticed to these facts. In some cases more than one pair of genes may influence the same character. These may interact
in different ways by adding, subtracting or modifying the character in question, or may inhibit or reverse the effect of another pair of
genes. This concept was introduced by bateson and is also known as ‘Bateson factor hypothesis’.gene interaction
The term gene interaction describes that several genes influence a particular characteristic. This does not mean, however, that two
or more genes or their products necessarily interact directly with one another to influence a particular phenotype. rather, the cellular
function of numerous gene products contributes to the development of a common phenotype. Correspondingly, gene interaction is
of two types- intragenic and intergenic.intragenic interaction
In the intragenic or interallelic interactions, the two alleles of a gene which are present on the same gene locus on the two homologous
chromosomes, react with each other in such a way as to produce an expression different from the normal dominant-recessive
phenotype, e.g., incomplete dominance, codominance, multiple alleles.
POST-MENDELIAN GENETICS
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