Write the scientific name of the organism Thomas Hunt Morgan and his colleagues worked with for their experiments.
Write the scientific name of the organism Thomas Hunt Morgan and his colleagues worked with for their experiments. Explain the correlation between linkage and recombination with respect to genes as studied by them.
2 Answers
Thomas Hunt Morgan and his colleagues used fruit fly, or Drosophila melanogaster to study linkage.
Morgan carried out several dihybrid crosses in Drosophila to study sex-linked genes. In one such experiment, he crossed yellow-bodied, white-eyed females with brown-bodied, red eyed males (wild type). He found that the two genes did not segregate independently of each other and the F2 ratio deviated from the 9:3:3:1 ratio, (expected when the two genes are independent).
Morgan attributed this due to the physical association or linkage of the two genes and coined the term linkage. He stated that higher the linkage between two genes, lesser are the chances of recombination.
Drosophila melanogaster
hey observed that two genes (located closely on a chromosome) did not segregate independently of each other (F2 ratio deviated significantly from 9 : 3 : 3 : 1).
Tightly linked genes tend to show fewer (lesser) recombinant frequency of parental traits / show higher (more) frequency of parental type.
Loosely linked genes show higher percentage (more) of recombinant frequency of parental traits / lower frequency percentage of parental type.
Genes present on same chromosome are said to be linked and the recombinant frequency depends on their relative distance on the chromosome.
Detailed Answer :
Thomas Hunt Morgan and his colleagues used fruit fly, or Drosophila melanogaster to study linkage.
Morgan carried out several dihybrid crosses in Drosophila to study sex-linked genes. In one such experiment, he crossed yellow-bodied, white-eyed females with brown-bodied, redeyed males (wild type). He found that the two genes did not segregate independently of each other and the F2 ratio deviated from the 9:3:3:1 ratio, (expected when the two genes are independent).
Morgan attributed this due to the physical association or linkage of the two genes and coined the term linkage. He stated that higher the linkage between two genes, lesser are the chances of recombination.