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Which of the following is true about linkage
$I.$ It is phenomenon in which more recombinants are produced in $F_{2}$-generation
$II.$ More parental combination are produced in $F_{2}$-generation
$III.$ Genotype which are present in $F_{1}$ hybrid. Reappear in high frequency in $F_{2}$-generation
$IV.$ It is a phenomenon in which two chromosome are linked
Only $I$
Only $II$
$I$ and $III$
$III$ and $IV$
Solution
Linkage and Recombination
Morgan carried out several dihybrid crosses in Drosophila to study genes that were sex linked. The crosses were similar to the dihybrid crosses carried out by Mendel in peas.
He observed that when two genes were grouped on the same chromosome, same genes are highly linked of associated and show low recombination.
When the genes are clearly present linked they show higher recombination.
Morgan attributed this due to the physical association or linkage of the two genes and coined the term linkage to describe this physical association of genes on a chromosome and the term recombination to describe the generation of non-parental gene combinations.
His student Alfred Sturtevant used the frequency of recombination between gene pairs on the same chromosome as a measure of the distance between genes and 'mapped' their position on the chromosome.
Morgan hybridized yellow bodied and white eyed females with brown bodied and red eyed male (wild type) (cross-$A$) and inter-crossed their $F_{1}$-progeny
Similar Questions
Match the following columns.
| Column $- I$ | Column $- II$ |
| $(w)$ Blood group | $(a)$ Polygenic inheritance |
| $(x)$ Skin colour | $(b)$ Aneuploidy |
| $(y)$ Mendelian disorder | $(c)$ Incomplete dominance |
| $(z)$ Chromosomal disorder | $(d)$ Sickle-cell anaemia |
| $(e)$ Co-dominance |
