| 释义 |
gene1 Biol.|dʒiːn|
[a. G. gen (W. Johannsen Elem. d. exacten Erblichkeitslehre (1909) 124), irreg. f. Gr. γεν- (see -gen).]
Each of the units of heredity which (except for polygenes) may be regarded as the controlling agents in the expression of single phenotypic characters and are usu. segments of a chromosome at fixed positions relative to each other; they were orig. defined as ultimate units of mutation and recombination, but are now best regarded as sequences of nucleotides within nucleic acid molecules each of which determines the primary structure of some protein or polypeptide molecule.
The term gene is used indiscriminately for both a genetic locus and an allele.
1911W. Johannsen in Amer. Naturalist XLV. 132, I have proposed the terms ‘gene’ and ‘genotype’..to be used in the science of genetics. The ‘gene’ is nothing but a very applicable little word, easily combined with others, and hence it may be useful as an expression for the ‘unit-factors’, ‘elements’ or ‘allelomorphs’ in the gametes, demonstrated by modern Mendelian researches. 1917T. H. Morgan in Ibid. LI. 520 The linkage relations of genes..have a very important bearing on the problem of the localization of genes in the germ plasm. 1925Nation 3 Oct. 19/1 If..in a given kind of plant there is a single ‘factor’ for flower colour and the flowers are blue or yellow, the gamete will bear either the blue factor (gene) or the yellow one, not both. 1930G. R. de Beer Embryol. & Evol. iii. 21 By introducing into an egg containing a weak female-producing gene a sperm containing a strong male-producing gene (as may be done by crossing moths of different races), it is possible to convert would-be females into males more or less completely. 1946Nature 6 July 30/2 The evidence indicates that resistance to blight is controlled by major genes, though minor genes determine the degree of susceptibility in susceptible varieties. 1955Sci. Amer. July 74/2 Heredity is determined by the chromosomes, the threadlike bodies in the nucleus of the cell, and by their subunits the genes. 1964G. H. Haggis et al. Introd. Molecular Biol. x. 260 The functional genes turn out to occupy a much greater chromosomal length than the genes defined by mutation or recombination. 1971Sci. Amer. Aug. 52/1 When we speak of genes, we usually have in mind the hereditary material—the DNA—in the chromosomes of the cell nucleus. Yet genes are also found outside the nucleus in the cytoplasm, notably in association with chloroplasts and mitochondria.
2. attrib. and Comb., as gene bank, a collection of different kinds of living cells, plants, or animals maintained as a repository of genetic material, esp. for developing new varieties or breeds or safeguarding the survival of existing ones; gene frequency (see quot. 1968); gene mutation, a mutation in which the change is confined to a single gene; gene pool, the stock of different genes in a breeding population.
1964Nature 11 Apr. 132/2 The Zoological Society of London..has set aside an area..to establish small flocks and herds which are to be bred under expert guidance{ddd}Great efforts will be made to ensure the success of this scheme—the *Gene Bank. 1971New Scientist 13 May 413/2 With animals, zoos may provide a last gene bank for species which cannot be protected in their natural habitats. 1980Daily Tel. 16 Jan. 8/3 A unique gene bank to prevent vegetable seeds with valuable disease resistance being lost for ever, is to be established in a joint Government–Oxfam venture.
1930R. A. Fisher Genet. Theory Nat. Selection i. 10 Even relatively intense selection will change the ratio p:q of the *gene frequencies relatively slowly. 1968R. Rieger Gloss. Genetics & Cytogenetics 170 Gene frequency, the proportion of one particular type of allele to the total of all alleles at this genetic locus in a breeding population.
1928Daily Tel. 11 Sept. 8/2 Whether X-rays could produce ‘*gene mutations’. 1930R. A. Fisher Genet. Theory Nat. Selection iii. 49 Gene-mutation..consists in a change in a single hereditary particle, or gene, into a gene of a new type.
1950T. Dobzhansky in Amer. Naturalist LXXXIV. 404 Every sexual species accordingly possesses a *gene pool, in which each gene may be represented by a certain number of alleles, and each chromosome by one or more structural variants. 1959New Biol. XXVIII. 90 Sexual reproduction provides such a mechanism in allowing gene-recombination; but..if unlimited in its scope it would inhibit diversification by randomizing the ‘gene pool’ in each generation. 1970Times 29 Dec. 10/6 There is a necessity to conserve a wide range of different genes in the ‘gene pool’ from which new strains can be selected.
Add:[2.] gene therapy Med., the technique or practice of introducing normal genes into cells in place of defective or missing ones in order to correct hereditary disorders.
1971Res. Communications Chem. Path. & Pharmacol. II. 587 (heading) *Gene therapy: a potentially invaluable aid to medicine and mankind. 1986Nature 20 Mar. 225/1 Within the next twelve months, it is likely that a proposal to perform gene therapy in humans will be submitted to local and national review bodies in the United States. 1991U.S. News & World Rep. 4 Nov. 66/2 An advisory committee at the National Institutes of Health..approved three more gene-therapy proposals to treat cancer and a deadly inherited form of high cholesterol. |