Inheritance is the transmission of genetically controlled characteristics from one generation to the next.
1. MONOHYBRID INHERITANCE AND THE LAW OF SEGREGATION : -
According to Mendel’s first law of inheritance, “The characteristics of an organism are determined by internal factors which occurs in pairs. Only one of a pair of such factors can be present in a single gamete. The ratio 3:1 is known as the monohybrid ratio.
2. DIHYBRID INHERITANCE AND THE LAW OF INDEPENDENT ASSORTMENT : -
According to Mendel’s second law of inheritance: In the inheritance of more than one pair of traits in a cross simultaneously, the factors responsible for each pair of traits are distributed independently to the gamete. The ratio of each phenotype of the seeds in the F2 generation is 9: 3: 3: 1. This is known as the dihybrid ratio.
Gametes from one hybrid
FUSION OF GAMETES
| |
RY |
Ry |
rY |
ry |
| RY |
RRYYRound yellow |
RRYy
Round yellow |
RrYY
Round |
RrYy
Round yellow |
| Ry |
RRYy
Round yellow |
RRyy
Round green |
RrYy
Round yellow |
Rryy
Round green |
| rY |
RrYY
Round yellow |
RrYy
Round yellow |
rrYY
Wrinkled yellow |
rrYy
Wrinkled yellow |
| ry |
RrYy
Round yellow |
Rryy
Round green |
rrYy
Wrinkled yellow |
rryy
Wrinkled green |
