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operon
operon in genetics , site on a bacterial chromosome containing genes that control protein synthesis (structural genes) together with a gene that determines whether the structural genes are active or not (operator gene). See nucleic acid .
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gene therapy
gene therapy the use of genes and the techniques of genetic engineering in the treatment of a genetic disorder or chronic disease. There are many techniques of gene therapy, all of them still in experimental stages. The two basic methods are called in vivo and ex vivo gene therapy. The in vivo ...
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gene
gene the structural unit of inheritance in living organisms. A gene is, in essence, a segment of DNA that has a particular purpose, i.e., that codes for (contains the chemical information necessary for the creation of) a specific enzyme or other protein. The strands of DNA on which the genes occur ...
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sarcoma
sarcoma , highly malignant tumor arising in connective- and muscle-cell tissue. It is the result of oncogenes (the cancer causing genes of some viruses) and proto-oncogenes (cancer causing genes in human cells). It may affect bone, cartilage, blood vessels, lymph nodes, and skin. See cancer ; neop...
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phenotype
phenotype Pheno derives from the Greek for display: the phenotype is the manifestation of the genetic make-up of the individual.‘Old Blue Eyes’ was the name given by many to Frank Sinatra. Having blue eyes is a trait that was part of his phenotype and is genetically determined, depen...
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genetics
genetics scientific study of the mechanism of heredity. While Gregor Mendel first presented his findings on the statistical laws governing the transmission of certain traits from generation to generation in 1856, it was not until the discovery and detailed study of the chromosome and the gene ...
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crossing over
crossing 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. The two homologous chromoso...
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recombination
recombination process of "shuffling" of genes by which new combinations can be generated. In recombination through sexual reproduction , the offspring's complete set of genes differs from that of either parent, being rather a combination of genes from both parents. In recombination by cross...
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Thomas Hunt Morgan
Thomas Hunt Morgan 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...
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natural selection
natural selection (‘survival of the fittest’) A complex process in which the total environment determines which members of a species survive to reproduce and so pass on their genes to the next generation. This need not necessarily involve a struggle between organisms....
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