Question

Briefly mention the contribution of T. H. Morgan in genetics.

Answer 1

Thomas Hunt Morgan (1866-1945), an American geneticist and Nobel Prize winner in 1933, is recognised as the “Father of Experimental Genetics” for his work on and discovery of linkage, crossing over, sex linkage, criss-cross inheritance, linkage maps, gene mutability, and so on. He is known as the fly man of genetics because he used fruit flies (Drosophila melanogaster) as research subjects in experimental genetics. His book “The Theory of Gene” primarily recognised genetics as a distinct discipline within biology. In 1910, he identified linkage and discriminated between linked and unlinked genes. Morgan and Castle’s (1911) “Chromosomal Theory of Linkage” argued that genes are located on chromosomes and ordered in a linear order. Morgan and Sturtevant (1911) discovered that the frequency of crossover (recombination) between two connected genes is exactly proportional to their distance. 1% recombination is equivalent to 1 centi Morgan (cM) or 1 map unit. He researched sex-linked inheritance and discovered a white-eyed male Drosophila in a red-eyed population, proving that the gene for eye colour is located on the X chromosome. The man passed genes on the X chromosome to the daughter, whereas the son received genes on the X chromosome from the mother. It is known as criss-cross inheritance.