| 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) |
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| duplication | 1. The act of duplicating, or the state of being duplicated; a doubling; a folding over; a fold. 2. <biology> The act or process of dividing by natural growth or spontaneous action; as, the duplication of cartilage cells. <mathematics> Duplication of the cube, the operation of finding a cube having a volume which is double that of a given cube. Origin: L. Duplicatio: cf. F. Duplication. Source: Websters Dictionary (01 Mar 1998) |
| duplication cyst | A congenital cystic malformation attached to or originating from any part of the alimentary canal, from the base of the tongue to the anus, which reproduces the structure of the adjacent alimentary tract. (05 Mar 2000) |
| duplication of chromosomes | A chromosome aberration resulting from unequal crossing over or exchange of segments between two homologous chromosomes; one chromosome of the pair loses a small segment, while the other gains this segment; the chromosome gaining the segment has undergone duplication while its homologue has undergone deletion. See: haemoglobin Lepore. (05 Mar 2000) |
| annular cataract | Congenital cataract in which a central white membrane replaces the nucleus. Synonym: disk-shaped cataract, life-belt cataract, umbilicated cataract. (05 Mar 2000) |
| arborescent cataract | An obsolete term for dendritic cataract. (05 Mar 2000) |
| atopic cataract | A cataract associated with atopic dermatitis. (05 Mar 2000) |
| axial cataract | A lenticular opacity in the visual axis of the lens. (05 Mar 2000) |
| black cataract | A cataract in which the lens is hardened and of a dark brown colour. In the 19th century, German black cataract meant gutta severa (q.v.). Synonym: cataracta brunescens, cataracta nigra. (05 Mar 2000) |
| blue cataract | Coronary cataract of bluish colour. Synonym: cataracta cerulea. (05 Mar 2000) |
| capsular cataract | A cataract in which the opacity affects the capsule only. (05 Mar 2000) |
| capsulolenticular cataract | A cataract in which both the lens and its capsule are involved. See: membranous cataract. (05 Mar 2000) |
| galactose cataract | A neonatal cataract associated with intralenticular accumulation of galactose alcohol. See: galactosaemia. (05 Mar 2000) |
| radiation cataract | A cataract caused by excessive or prolonged exposure to ultraviolet rays, X-rays, radium, beta rays, gamma rays, heat, or radioactive isotopes. (05 Mar 2000) |
| vascular cataract | Congenital cataract in which the degenerated lens is replaced with mesodermal tissue. Synonym: cataracta adiposa, cataracta fibrosa. (05 Mar 2000) |