Question

Explain the law of segregation in detail.

Answer 1

The law of segregation states that the two alleles of a gene separate during gamete formation, so each gamete receives only one allele.

1. In a diploid organism, a trait is controlled by a pair of alleles, such as Tt. 
2. The alleles remain distinct and do not blend. 
3. During gamete formation, Tt produces T and t gametes in equal proportions. 
4. Random fertilisation restores the pair of alleles in the offspring. 
5. Selfing F₁ heterozygotes (Tt × Tt) gives genotypes TT, Tt, Tt and tt: genotypic ratio 1 : 2 : 1 and, with complete dominance, phenotypic ratio 3 : 1.

Alleles segregate without losing their identity, explaining the reappearance of recessive traits in F₂.