Question

What type of progeny would you expect if genes are completely linked?

• A. No progeny survive
• B. Parental types only
• C. Parental types and recombinants both
• D. Only recombinanats

Answer 1

The correct option is B Parental types only

Genetic linkage is the tendency of alleles that are close together on a chromosome to be inherited together during the meiosis phase of sexual reproduction. Complete linkage is very simply the phenomenon by which a group of genes on a chromosome is inherited as such without any change, from one generation to the next and so on and because there is no change or basically recombination of genes, there should be parental combinations only and no recombinants. Morgan (1919) reported a complete linkage in Drosophila. When ordinary male wild fly with grey body and normal wings was crossed with female having black body and vestigial wings, the F₁ hybrids were all grey bodied and normal winged (with dominant characters). But the F₂ ratio deviated significantly from the Mendelian 9:3:3:1. The number of recombinants were considerably lesser, and most of them had the parental phenotypes, grey bodied and normal winged or black bodied and vestigial winged in nearly equal number, thus indicating the complete linkage.