| segmentation gene | <molecular biology> Genes required for the establishment of segmentation in the embryo. In Drosophila about 20 such genes are required. A development pattern of the embryo of the fruit fly Drosophila where the embryo looks like a stack of discs. Each disc is a segment, and each segment consists of two compartments (an anterior and posterior). Various parts of the adult fruit fly (wings, legs, eyes, etc.) arise from specific segments. (09 Oct 1997) |
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| segment polarity gene | <molecular biology> A segmentation gene, responsible for specifying anterior posterior polarity within individual embryonic segments. In Drosophila, there are at least 10 such genes, for example gooseberry. (18 Nov 1997) |
| housekeeping gene | <molecular biology> The genes which are expressed in all cells and which code for molecules that are necessary for basic maintenance and essential cellular functions. (09 Oct 1997) |
| hox gene | <molecular biology> Homeobox containing genes of vertebrates. (18 Nov 1997) |
| human gene therapy | <molecular biology, technique> Insertion of normal DNA directly into cells to correct a genetic defect. (09 Oct 1997) |
| HuP gene | <molecular biology> Human equivalents of the Pax genes. (18 Nov 1997) |
| S gene complex | <molecular biology> Genes coding for molecular components of the pollen stigma recognition system in the cabbage genus Brassica). The gene products govern the self incompatibility response and include a glycoprotein found on the stigma surface and a lectin on the pollen grain surface that binds to the stigma glycoprotein. (18 Nov 1997) |
| single-gene diseases | Hereditary disorders caused by a change (mutation) in a single gene. There are thousands of single-gene diseases including achondroplastic dwarfism, huntington disease, cystic fibrosis, sickle cell disease, duchenne muscular dystrophy, and haemophilia. Single-gene diseases typically describe classic simple mendelian patterns of inheritance (as autosomal dominant, autosomal recessive, and x-linked traits) by comparison with polygenic diseases. (12 Dec 1998) |
| single gene disorder | Hereditary disorder caused by a mutant allele of a single gene (for example, Duchenne muscular dystrophy, retinoblastoma, sickle cell disease). Compare: polygenic disorders. (09 Oct 1997) |
| somatic cell gene therapy | The repair or replacement of a defective gene within somatic tissue. (09 Oct 1997) |
| split gene | Non-coding, intervening sequences of DNA that are transcribed, but are removed from within the primary gene transcript and rapidly degraded during maturation of messenger RNA. most genes in the nuclei of eukaryotes contain introns, as do mitochondrial and chloroplast genes. (12 Dec 1998) |
| neurogenic gene | Best described in Drosophila, genes that are required to determine a neuronal fate. Examples: Notch, Delta. (18 Nov 1997) |
| structural gene | A gene that codes for a product (e.g. An enzyme, structural protein, tRNA), as opposed to a gene that serves a regulatory role. (18 Nov 1997) |
| nif gene | <molecular biology> The complex of genes in nitrogen fixing bacteria that code for the proteins required for nitrogen fixation, particularly the nitrogenase. Present as an operon in Klebsiella and carried on plasmid in Rhizobium which inhabit the roots of leguminous plants. (13 Nov 1997) |
| d4dr gene | <molecular biology> A gene which regulates a protein that plays a role in transmitting messages carried by dopamine between neurons (brain cells). A particular form of the gene may have an affect on an individual's personality since it seems to occur in individuals with novelty-seeking behaviour. (09 Oct 1997) |