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sir, what is Mendel's law of inheritance in one gene?
An analysis of genetic crosses depends upon an understanding of Mendel's two laws:

• The principle of segregation (First Law): The two members of a gene pair (alleles) segregate (separate) from each other in the formation of gametes. Half the gametes carry one allele, and the other half carry the other allele.

• The principle of independent assortment (Second Law): Genes for different traits assort independently of one another in the formation of gametes.
In practice, the manifestation of Mendel's laws is seen by characteristic ratios of phenotypic classes, such as 3:1 and 9:3:3:1. Further, the Mendelian principles just stated include the simple assumption that one allele is dominant to the other allele.

In the time since Mendel's original experiments, we have come to learn that there are extensions to Mendelian principles, including the fact that some alleles are incompletely dominant, that some genes are sex-linked, and that some pairs of genes do not assort independently because they are physically linked on a chromosome.


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