Law of Segregation ( Genes are Distributed without mixing )
Definition :
During fertilization, two members of allelic pair remain together without mixing and these allele pairs separate or segregate, during gamete formation.
Introduction :
When a pair of contrasting characters or yellow/green factors as in fig. are brought together such as allele pair remain together without being contaminated/mixing up and when gametes are formed in F2 generation from this hybrid (F1), the two characters separate from this character and only one can enter each gamete.
Subtitle – 1 :
- Mendel postulated that the color of seeds was controlled by “factor” that was transmitted to the offspring by means of gametes. This hereditary factor which is now called the gene could be transmitted without mixing with other genes. Now, this gene in F1 hybrid can be segues gated/separated into different offspring during gamete formation, for this reason, Nendel called it “Law of Segregation”
- In the hybrid F1, each gene is segregated and enters a different gamete. Half of the gametes will have gene A, and the other half, a because each individual produces two types of gametes in each sex, there are four possible combinations in F2. This gives, as a result, the proportion 1 : 2 : 1 , corresponding to 25% of plants with pure yellow seeds (AA), 50% with hybrid yellow seeds (Aa), and 25% with pure green seeds (aa).
Important Note :
Mendel’s results can now be explained in terms of the behavior of chromosomes and genes. The genes present in the chromosomes are found in pairs called alleles (or alleles can be simply called the two forms dominant and recessive of the same gene)
The genes present in the chromosomes are found in pairs called alleles. In each homologous chromosome, the gene for each trait occurs at a particular point called a locus.
(Genes in different chromosomes are distributed independently during meiosis)