Laws of Mendel
The father of modern genetics, “Gregor Mendel,” was the first person to discover the principle of heredity. He conducted various experiments, including one on pea plants in his garden, and he observed how the pattern of inheritance changed from one generation to the next.
His experiment on peas helped him to propose three of Mendel’s laws of inheritance, named as follows:
- Law of Segregation
- Law of Independent Assortment
- Law of Dominance
Also Read: Law of Segregation and Dominance
First, Mendel studied one gene in the plant using a monohybrid cross. In this, he only considered a single character, which was the height of the plant on a pair of peas with one contrasting trait. Next, he studied two genes in the plant using a dihybrid cross.
Characters with their Contrasting Traits
Mendel chose 7 contrasting characters for his hybridization experiments which are as follows –
Characters |
Traits |
---|---|
Plant Height |
Tall or Dwarf |
Seed Shape |
Round or Wrinkled |
Seed Color |
Yellow or Green |
Pod Shape |
Yellow or Green |
Pod Color |
Inflated or Constricted |
Flower Color |
Violet or White |
Flower Position |
Axial or Terminal |
Dihybrid Cross: Phenotypic Ratio, Definition, Diagram and Overview
A dihybrid cross is a mating experiment that takes place between 2 individuals who are identical hybrids for two traits. In a dihybrid cross, the cross happens between the two traits that are under observation. The two genes of the traits under study are located on different pairs of homologous chromosomes and assort independently during gamete formation. The dihybrid cross-phenotypic ratio is 9:3:3:1.