6 minute read

History of Genetics - The Molecular Gene

Science EncyclopediaScience & Philosophy: Heterodyne to Hydrazoic acidHistory of Genetics - Gregor Johann Mendel, Rediscovery, The Chromosome Theory Of Heredity, Culture Of Heredity, Fine Structure Of The Gene

The Molecular Gene

It has been remarked that molecularizing the gene, far from establishing it as a discrete entity, had the opposite effect, fragmenting and destroying it. True, ever since the 1930s there had been discussion of what was euphemistically called "position effect"—the idea that a gene defined by its function can suffer two distinct mutations and that even if one normal example of the two mutated sites is present in the cell, the gene will only function when both lie on the same chromosome. The neat coincidence between the gene defined by function, by location, and by mutation was broken in these cases. But unraveling the mystery of protein synthesis, in which the function of the genes is to specify which amino acids are to be incorporated into the protein and in what order, revealed further complexity. It turned out that the genetic message (messenger RNA) from many genes is cut into parts, some fragments being rejected (known as introns) and the remainder (exons) incorporated into the chain that is transcribed into a sequence of amino acids. Different parts of the same message may thus be incorporated into different gene products. To those working in the field, these complexities are par for the course. The word gene has not died and been buried, but the context in which it is used tells the informed listener in what sense to understand the term. The simple conception of the Mendelian factor or gene of classical genetics has surely suffered a major series of revisions. The simple picture of genes like beads on a string, though essential to get a hand-hold on the problem, has not survived. But the early claim of Richard Goldschmidt that any discreteness of the gene be dropped, and that the chromo-some be considered one continuous developmental unit, has never been accepted. There are codons in the DNA for starting and terminating the genetic message. Genes are interspersed with non-coding regions in the DNA. But the relation between the DNA and the proteins around it is a subtle and dynamic one.

Since Johannsen introduced the term "gene" first in 1909 it has served as a flexible concept, suffering many revisions and acquiring many meanings. In the process the extreme hereditarian view of DNA as dictating the life of the cell has been undermined by the discovery of a hierarchy of interactions between DNA and proteins. Genetics has in truth found its place at the core of biology, and in doing so it has revealed a machinery of the cell more intricate and subtle than could ever have been imagined.

BIBLIOGRAPHY

PRIMARY SOURCES

Bateson, William. "After Dinner Speech." In Report of the Third International Conference 1906 on Genetics: Hybridisation (Cross-Breeding of Genera or Species, the Cross-Breeding of Varieties, and General Plant Breeding), edited by the Reverend W. Wilks, 91. London: Royal Horticultural Society, 1907.

Corcos, Alain F., and Floyd V. Monaghan. Gregor Mendel's Experiments on Plant Hybrids: A Guided Study. New Brunswick, N.J.: Rutgers University Press, 1993.

Crick, Francis. What Mad Pursuit: A Personal View of Scientific Discovery. New York: Basic Books, 1988. See especially chapter 8, "The Genetic Code."

Crick, Francis H. C., Leslie Barnett, Sydney Brenner, and R. J. Watts-Tobin. "General Nature of the Genetic Code for Proteins." Nature 192 (1962): 1227–1232.

De Candolle, Alphonse. Histoire des sciences et des savants depuis deux siècles, d'après l'opinion des principales académies ou sociétés scientifique. Edited by Bruno Latour. Paris: Fayard, 1987.

Galton, Francis. Inquiries into Human Faculty and Its Development. London: Macmillan, 1883. (Quotation taken from the slightly altered reprint, London: Dent; and New York: Dutton, 1908.)

Johannsen, Wilhelm. "The Genotype Conception of Heredity." American Naturalist 45 (1911): 329–363.

Stern, Curt, and Eva R. Sherwood. The Origin of Genetics: A Mendel Source Book. San Francisco: Freeman, 1966.

Watson, James D. The Double Helix: A Personal Account of the Discovery of the Structure of DNA. Edited by Gunther S. Stent. New York: Norton Critical Editions, 1980.

Wilkins, Maurice. The Third Man of the Double Helix. Oxford and New York: Oxford University Press, 2003.

SECONDARY SOURCES

Adams, Mark. B., ed. The Wellborn Science: Eugenics in Germany, France, Brazil, and Russia. New York: Oxford University Press, 1990. See especially Adams's essay "Towards a Comparative History of Eugenics," 217–231.

Allen, Garland, E. Thomas Hunt Morgan: The Man and His Science. Princeton. N.J.: Princeton University Press, 1978.

Baxter, A., and John Farley. "Mendel and Meiosis." Journal of the History of Biology 12 (1979): 137–173.

Beurton, Peter J., Raphael Falk, and Hans-Jörg Rheinberger, eds. The Concept of the Gene in Development and Evolution: Historical and Epistemological Perspectives. Cambridge, U.K., and New York: Cambridge University Press, 2000. See especially the essay on Seymour Benzer by Frederick L. Holmes.

Brock, Thomas D. The Emergence of Bacterial Genetics. Cold Spring Harbor, N.Y.: Cold Spring Harbor Laboratory, 1990.

Chadarevian, Soraya de. "Sequences, Conformations, Information: Biochemists and Molecular Biologists in the 1950s." Journal of the History of Biology 29 (1996): 361–386.

Gillham, Nicholas. A Life of Sir Francis Galton: From African Exploration to the Birth of Eugenics. New York: Oxford University Press, 2001.

Henig, Robin Marantz. The Monk in the Garden: The Lost and Found Genius of Gregor Mendel, the Father of Genetics. Boston: Houghton Mifflin, 2000.

Kevles, Daniel J. In the Name of Eugenics: Genetics and the Uses of Human Genetics. Cambridge, Mass., and London: Harvard University Press, 1995.

Kohler, Robert. The Lords of the Fly: Drosophila Genetics and the Experimental Life. Chicago: University of Chicago Press, 1994.

Magnello, M. Eileen. "The Non-Correlation of Biometrics and Eugenics: Rival Forms of Laboratory Work in Karl Pearson's Career at University College London." History of Science 37 (1999): 79–106, 123–150.

Meijer, Onno G. "De Vries No Mendelian." Annals of Science 42 (1985): 89–232.

Morange, Michel. A History of Molecular Biology. Translated by Matthew Cobb. Cambridge, Mass., and London: Harvard University Press, 1998.

Olby, Robert. "Constitutional and Hereditary Disorders." In Companion Encyclopedia of the History of Medicine, edited by W. F. Bynum and Roy Porter, 412–437. London and New York: Routledge, 1993.

——. "The Dimensions of Controversy: The Biometric-Mendelian Debate." British Society for the History of Science 22 (1989): 299–320.

——. "Horticulture: The Font for the Baptism of Genetics." Nature Reviews Genetics 1 (2000): 65–70.

——. "The Monk in the Garden, by Robin M. Henig." Perspectives in Biology and Medicine 46 (2003): 142–145.

——. The Path to the Double Helix. London: Macmillan, 1974.

Orel, Vítezslav. Gregor Mendel: The First Geneticist. Translated by Stephen Finn. Oxford and New York: Oxford University Press, 1996.

Paul, Diane B. Controlling Human Heredity: 1865 to the Present. Atlantic Highlands, N.J.: Humanities Press, 1995.

Peters, James A. Classic Papers in Genetics. Englewood Cliffs, N.J.: Prentice Hall, 1959.

Pick, Daniel. Faces of Degeneration. A European Disorder, c. 1848–c. 1918. Cambridge, U.K., and New York: Cambridge University Press, 1989.

Pinto-Correia, Clara. The Ovary of Eve: Egg and Sperm and Pre-formation. Chicago and London: University of Chicago Press, 1997.

Roe, Shirley A. Matter, Life, and Generation: Eighteenth Century Embryology and the Haller-Wolff Debate. Cambridge, U.K., and New York: 1981.

Roll, Hansen. "The Crucial Experiment of Wilhelm Johannsen." Biology and Philosophy 4 (1989): 303–329.

Russell, Nicholas. Like Engend'ring Like: Heredity and Animal Breeding in Early Modern England. Cambridge, U.K., and New York: Cambridge University Press, 1986.

Wood, Roger J., and Vítezslav Orel. Genetic Prehistory in Selective Breeding: A Prelude to Mendel. Baltimore: Johns Hopkins University Press, 2003.

Robert Olby

Additional topics