Question

What is the fewest number of genes which must be examined to confirm Mendel’s law of independent assortment?

Answer 1

According to the law of independent assortment of Mendel, the alleles of two more genes get sorted into gametes independent of each other. The allele received for one gene does not influence the allele received for another gene.
His experiment always portrayed that the combinations of traits of the progeny which are always different from their parental traits. Based on this, Mendel formulated the Law of Independent Assortment.
The Law of Independent Assortment states that during a dihybrid cross, an assortment of eacb pair of traits is independent of the other. It can be said that, during formation of gamete, one pair of trait segregates from another pair of traits independently. This gives each pair of characters a chance of expression.

In the dihybrid cross, Mendel chose round-yellow seed and wrinkled green seed and crossed them. He obtained only round yellow seeds in the F₁generation. Later, self-pollination of F₁ progeny gave four different combinations of seeds in the F₂generation. He obtained round-yellow, wrinkled-yellow, round green and wrinkled green seeds in the phenotypic ratio 9:3:3:1.
The phenotypic ratio 3:1 of yellow: green colour and the ratio 3:1 of the round: wrinkled seed shape during monohybrid cross was retained in the dihybrid cross as well. He concluded that characters are distributed independently and inherited independently. Based on this observation, he developed his third law – Law of Independent Assortment.
The dihybrid crosses between the parental genotype RRYY (round yellow seeds) and rryy (green wrinkled seeds) explains the law. Here the chances of formation of gametes with the gene R and the gene r are 50:50. Also, the chances of formation of gametes with the gene Y and the gene y are 50:50. Thus, each gamete should have either R or r and Y or y.
The Law of Independent Assortment states that the segregation of R and r is independent of the segregation of Y and y. This results in four types of gametes RY, Ry, rY, and ry. These combinations of alleles are different from their parental combination which is RR, YY, rr and yy.

Therefore, Mendel’s Law of Independent Assortment states the inheritance of one pair of genes is independent of the inheritance of the other pair.
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