Dna

The law of dominance and recessiveness

Gregor Mendel was the father of heredity. His experiments with pea plants established principles of dominance and recessiveness in phenotypic variation.

i belive that the definition of recessive and dominant laws is from a genes with a type of Rr R:is for the type of ao it is the law of dominant ang the r: is unless type of oo and theres no type unless thee oo it is from the laws of the recessiveness

- Some "alleles" (hereditary traits) are dominant, and others are recessive.

- If a pure dominant trait is bred with a recessive trait, their offspring will show 75% presence of the dominant trait, and 25% presence of the recessive trait in the F1 (first filial) generation.

- If a plant with a dominant trait from the F1 generation (carrier, heterozygous dominant) is bred with a plant that shows a recessive trait, their offspring will display at 50/50 probability of dominance versus recessiveness. Thus, alleles expressing a particular trait via dominance/recessiveness, in the case of the pea plants, take the form of two alleles that combine to express a particular version. This later has been shown to be homozygous dominance/recessiveness, or heterozygous dominance.