Conclusions drawn from the Monohybrid Crosses

From the results of his monohybrid crosses, following conclusions were obtained :-

1 .       Law of Unit or Paired Factors (Postulate 1)

A character is represented in an organism (diploid) by at least two factors. The two factors lie on the two homologous chromosomes at the same locus. They may represent the same (homologous, e.g; TT in case of pure tall Pea plants) or alternate expression (heterozygous, e.g; Tt in case of hybrid tall Pea plants) of the same character. Factors representing the alternate or same form of a character are called alleles or allelomorphs.

2 .       Law of Dominance (Postulate 2)

It states, "When a pair of alleles or allelomorphs are brought together in F₁ hybrid, then only one of them expresses itself, masking the expression of other completely."

e.g; In Tt-F₁ hybrid

(tall)

Only 'T' expresses itself - so dominant and 't' is masked - so recessive.

3 .       Law of Segregation or Law of Purity of Gametes (Postulate 3)

It states that, "When a pair of alleles or allelomorphs are brought together in F₁ hybrid, they remain together (coexist) without mixing or contaminating or blending with each other and separate complete during formation of gamete (gametogenesis)."

It is also known as 'Law of purity of gametes' because each gamete is pure in itself, i.e; having either T (i.e; factor for tallness) or t (i.e; factor for dwarfness).