Q.8 Name the Nobel awardee, who provided the first direct evidence that different genes are
physically located on the same chromosome by X–linked pattern of inheritance in
Drosophila.
T.H. Morgan provided the first direct evidence that genes are physically located on the same chromosome through X-linked inheritance patterns in Drosophila, earning the 1933 Nobel Prize in Physiology or Medicine.
Question Breakdown
This question tests historical milestones in genetics, pivotal for molecular biology and genetics students preparing for exams like GATE Life Sciences, linking Mendelian inheritance to chromosomal theory.
Option Explanations
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Gregor Mendel: Known as the father of genetics for pea plant experiments establishing laws of segregation and independent assortment (1860s), but worked pre-chromosome discovery and used no Drosophila.
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T.H. Morgan: Discovered white-eyed Drosophila mutant (1910); breeding showed X-linked inheritance (males only initially), proving genes reside on sex chromosomes and demonstrating linkage/recombination.
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H.J. Muller: Morgan’s student; Nobel 1946 for X-ray induced mutations proving genetic material mutability, but did not discover chromosomal gene location or X-linkage.
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Watson and Crick: Nobel 1962 for DNA double helix structure (1953), explaining molecular basis of inheritance, not chromosomal mapping or Drosophila evidence.
Introduction to Nobel Awardee Genetics Discovery
Nobel awardee T.H. Morgan provided the first direct evidence genes are physically located on the same chromosome using X-linked pattern of inheritance in Drosophila. His 1910 white-eyed fly experiments confirmed chromosome theory.
Morgan’s Drosophila Breakthrough
Morgan observed white eyes only in males from red-eyed parents, predicting X-linkage: females XX (carrier possible), males XY (express if inherited). Reciprocal crosses confirmed genes on X chromosome, with linkage maps via recombination.
Scientists Comparison
| Scientist(s) | Contribution | Link to Chromosomal Genes? |
|---|---|---|
| Gregor Mendel | Pea laws of inheritance | Pre-chromosome; no cytogenetics |
| T.H. Morgan | X-linked white-eye in flies | First direct evidence, Nobel 1933 |
| H.J. Muller | X-ray mutagenesis | Mutations, not location proof |
| Watson and Crick | DNA structure | Molecular mechanism, post-Morgan |
Morgan bridged Mendel to modern genetics.
Relevance in Molecular Genetics
Foundational for genomics, genetic engineering; essential for GATE questions on inheritance patterns and Drosophila model in research.
