Question

1. Mendel’s Law of Independent Assortment does not always hold true. Some genes are linked, and offspring that inherit one gene will also inherit others. In these cases where genes are linked, Explain how phenotypic traits that are potentially deleterious can persist in a population.

Answer 1

The law of indepwndent assortment holds true only upto their where two different genes are on separate chromosome . When the genes are present on a separate chromosomes ,the two allele of one gene will segregate into gametes independently of the two alleles of the other gene . But if we consider the case where two genes are on the same chromosome ,then they will be linked and will segregate together during meiosis ,producing only two kinds of gamete . Phenotypic traits that are potentially deleterious can persist in a population because of the linked genes and their tendency to come up together. For instance ,if the genes for two disease were on the same chromosome and the homozygous dominant one's was crossed with a homozygous double recessive ,the F1 hybrid offspring would be double heterozygous dominant . Since the two genes are linked otogether on the other chromosome ,only two different gametes are formed . Therfore instead of 16 different genotypes in the F2 offspring only three are possible and instead of 4 different phenotypes only the original two will exist . So there is only chances of segregation of physically linked genes .