Thomas Hunt Morgan

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Morgan, Thomas Hunt,

1866–1945, American zoologist, b. Lexington, Ky., Ph.D. Johns Hopkins, 1890. He was professor of experimental zoology at Columbia (1904–28) and from 1928 was director of the laboratory of biological sciences at the California Institute of Technology. He is noted for his ingenious demonstration of the physical basis of heredity and the importance of the gene, using in his research the fruit fly, Drosophila. He described the phenomena of linkage and crossing overcrossing over,
process in genetics by which the two chromosomes of a homologous pair exchange equal segments with each other. Crossing over occurs in the first division of meiosis. At that stage each chromosome has replicated into two strands called sister chromatids.
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, which he and his students utilized to map the linear arrangement of genes along the chromosome. Morgan received the 1933 Nobel Prize in Physiology or Medicine. His books, classics in the literature of genetics, include The Physical Basis of Heredity (1919), Mechanism of Mendelian Heredity (rev. ed. 1923), Evolution and Genetics (1925), The Theory of the Gene (rev. ed. 1928), and Embryology and Genetics (1934).

Morgan, Thomas Hunt

 

Born Sept. 25, 1866, in Lexington, Ky.; died Dec. 4, 1945, in Pasadena, Calif. American biologist and one of the founders of genetics. President of the National Academy of Sciences of the USA (1927–31).

Morgan graduated from the University of Kentucky in 1886 and from Johns Hopkins University in Baltimore in 1891. From 1891 to 1904 he was a professor at Bryn Mawr College and from 1904 to 1928 at Columbia University in New York City. From 1928 to 1945, Morgan was director of the William G. Kerckhoff Laboratories at the California Institute of Technology in Pasadena.

Morgan’s first works were devoted to experimental embryology; subsequent works dealt with regeneration and sex determination in animals. From 1910 he studied the inheritance of mutations, which were discovered in a new experimental subject of genetic research—the fruit fly, Drosophila. This study provided Morgan and his associates (A. Sturtevant, H. Muller, and C. Bridges) with an experimental corroboration of the physiological foundations of heredity (the corpuscular nature of genetic material [the genes], the linear arrangement of genes in the chromosomes, the principles of the mutational variability of genes, and the cytogenetic mechanisms of the hereditary transmission of genes). This genetic research confirmed the chromosome theory of heredity and made it possible to complete the fundamental aspects of that theory.

The regularities of gene linkage and crossing-over discovered by Morgan and his associates provided a complete explanation for the cytological mechanism of Mendel’s laws and served as a stimulus for the development of the genetic foundations of the theory of natural selection. Morgan was awarded a Nobel Prize in 1933. He became an honorary member of the Academy of Sciences of the USSR in 1932.

WORKS

In Russian translation:
Strukturnye osnovy nasledstvennosti. Moscow-Petrograd, 1924.
Teoriia evoliutsii v sovremennom osveshchenii. Moscow-Leningrad, 1926.
Teoriia gena. Leningrad, 1927.
Eksperimental’nye osnovy evoliutsii. Moscow-Leningrad, 1936.
Razvitie i nasledstvennost’ Moscow-Leningrad, 1937.
Izbrannye raboty po genetike. Moscow-Leningrad, 1937.

REFERENCES

Lobashev, M. E. “T. G. Morgan: Osnovatel’ teorii gena.” Genetika, 1966, no. 11.
Sturtevant, A. “Vospominaniia o T. G. Morgane.” Priroda, 1968, no. 8, pp. 91–97.
Sturtevant, A. H. “T. H. Morgan.” Biographical memoirs, 1959, no. 33, pp. 283–325.
Allen, G. E. “T. H. Morgan and the Emergence of a New American Biology.” Quarterly Review of Biology, 1969, vol. 44, no. 2, pp. 168–88.

A. E. GAISINOVICH

Morgan, Thomas Hunt

(1866–1945) geneticist; born in Lexington, Ky. Trained as an embryologist, he became a biology professor at Bryn Mawr (1891–1904), where he wrote his first major book, Regeneration (1901). He became a professor at Columbia University (1904–28), and began his revolutionary genetic investigations of the fruit fly Drosophila (1908). Initially skeptical of Gregor Mendel's research, Morgan performed rigorous experiments which demonstrated that genes were indeed discrete chromosomal units of heredity. In 1910 he discovered sex-linkage in Drosophila, and postulated a connection between eye color in fruit flies and human color blindness. With his "fly room" colleagues, he mapped the relative positions of genes on Drosophila chromosomes, then published his seminal book, The Mechanisms of Mendelian Heredity (1915). Followed by some of his Columbia group, he moved to the California Institute of Technology (Caltech) (1928) to continue Drosophila research. In 1933 he received the Nobel Prize in physiology for his studies of the role of chromosomes in heredity. He remained at Caltech until his death, performing administrative duties and pursuing investigations of inheritance in Drosophila, mammals, birds, and amphibians.
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