| gene conversion | <molecular biology> A phenomenon in which alleles are segregated in a 3:1 not 2:2 ratio in meiosis. May be a result of DNA polymerase switching templates and copying from the other homologous sequence or a result of mismatch repair (nucleotides being removed from one strand and replaced by repair synthesis using the other strand as template). (18 Nov 1997) |
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| gene deletion | The total loss (or absence) of a gene. Gene deletion plays a role in birth defects and in the development of cancer. (12 Dec 1998) |
| gene disorder | Hereditary disorder caused by a mutant allele of a single gene (e.g., Duchenne muscular dystrophy, retinoblastoma, sickle cell disease). Compare polygenic disorders. (05 Mar 2000) |
| gene disruption | Use of both in vitro and in vivo recombination to substitute an easily selected mutant gene for a wild-type gene. (09 Oct 1997) |
| gene divergence | The difference (expressed as a percentage) in the nucleotide sequencesbetween two related genes that developed from the same ancestral gene. (09 Oct 1997) |
| gene dosage | <molecular biology> Number of copies of a particular gene locus in the genome, in most cases either one or two. (18 Nov 1997) |
| gene dosage compensation | The putative mechanism that adjusts the X-linked phenotypes of males and females to compensate for the haploid state in males and the diploid state in females. It is now largely ascribed to lyonization which compensates the mean of the dose but not its variance, which is greater in females. (05 Mar 2000) |
| gene dosage effect | In codominant alleles, the more or less linear relationship between the phenotypic value and the number of genes of one type substituted by another type. (05 Mar 2000) |
| gene duplication | <molecular biology> A class of DNA rearrangement that generates a supernumerary copy of a gene in the genome. This would allow each gene to evolve independently to produce distinct functions. Such a set of evolutionarily related genes can be called a gene family. (18 Nov 1997) |
| gene, evolutionarily conserved | A gene that has remained essentially unchanged throughout evolution. Conservation of a gene indicates that it is unique and essential. There is not an extra copy of that gene with which evolution can tinker. And changes in the gene are likely to be lethal. (12 Dec 1998) |
| gene expression | <molecular biology> The full use of the information in a gene via transcription and translation leading to production of a protein and hence the appearance of the phenotype determined by that gene. Gene expression is assumed to be controlled at various points in the sequence leading to protein synthesis and this control is thought to be the major determinant of cellular differentiation in eukaryotes. (18 Nov 1997) |
| gene expression regulation | Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action at the level of transcription or translation. These processes include gene activation and genetic induction. (12 Dec 1998) |
| gene expression regulation, archaeal | Any of the processes by which cytoplasmic or intercellular factors influence the differential control of gene action in archaea. (12 Dec 1998) |
| gene expression regulation, bacterial | Any of the processes by which cytoplasmic or intercellular factors influence the differential control of gene action in bacteria. (12 Dec 1998) |
| gene expression regulation, developmental | Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control of gene action during the developmental stages of an organism. (12 Dec 1998) |