allotypic marker |
Synonym: allotype.
(05 Mar 2000) |
genetic marker |
A gene which has an easily identifiable phenotype so that one can tell apart cells or individuals which have the gene and those which do not have it. Such a gene can also be used as a probe to mark cell nuclei or chromosomes so that they can easily be isolated or identified from other nuclei or chromosomes later.
(09 Oct 1997) |
marker |
An identifiable physical location on a chromosome (for example, restriction enzyme cuttingsite, gene) whose inheritance can bemonitored. Markers can beexpressed regions of DNA (genes) or some segment of DNA with no knowncoding function but whose pattern of inheritance can be determined.
See: restriction fragment length polymorphism.
(09 Oct 1997) |
marker chromosome |
An abnormal chromosome that is distinctive in appearance but not fully identified. For example, the fragile x chromosome was once called the marker x.
(12 Dec 1998) |
marker enzyme |
<enzyme> An enzyme that is used to identify a specific cell type, cell organelle, or cell component.
(05 Mar 2000) |
marker gene |
Gene that confers some readily detectable phenotype on cells carrying the gene, either in culture or in transgenic or chimeric organisms. Gene could be an enzymic reporter gene, a selectable marker conferring antibiotic resistance or a cell membrane protein with a characteristic epitope.
(18 Nov 1997) |
marker locus |
A locus on a chromosome or in a stretch of DNA that can be identified (e.g., a restriction fragment length polymorphism) and can serve in linkage analysis and in the isolation of a disease gene.
See: linkage marker.
(05 Mar 2000) |
marker, object |
<microscopy> A small abrasive stylus, set in a rotating holder mounted on the lower end of the drawtube. The desired part of the specimen is placed in the centre of the field, and the abrasive point is pressed against the slide or cover, and rotated. It describes a tiny circle around the desired object field.
(05 Aug 1998) |
marker trait |
A trait that may be of little importance in itself but which by association, linkage, or other means facilitates the detection, anticipation, or understanding of a disease or (for genetic diseases) the localization of the causative gene on the karyotype.
(05 Mar 2000) |
cell marker |
<cell biology> Biochemical or genetic characteristics which distinguish and discriminate between different cell types.
(26 Mar 1998) |
cell surface marker |
<cell biology> Any molecule characteristic of the plasma membrane of a cell or in some cases of a specific cell type. 5' nucleotidase and Na/K ATPase are often used as plasma membrane markers.
(26 Mar 1998) |
selectable marker |
<molecular biology> A gene whose expression allows one to identify cells that have been transforrned or transfected with a vector containing the marker gene.
(09 Oct 1997) |
hypoxanthine-guanine phosphoribosyl tranferase marker |
The gene which codes for the enzyme hypoxanthine-guanine phosphoribosyl transferase. It is a selectable marker because cells which have a defective version of this gene are resistant to poisoning by toxic purine derivatives which result from the metabolic pathway that the HGPRT enzyme catalyses. (The purine derivatives are toxic because they incorporate into DNA as a result of the HGPRT enzyme's actions). Because the defective gene cannot produce the enzyme, no toxic purine derivatives are produced, the gene can therefore be selected for.
(09 Oct 1997) |
surrogate marker |
<biology> A laboratory measurement of biological activity within the body that indirectly indicates the effect of treatment on disease state.
CD4 cell counts and viral load are examples of surrogate markers in HIV infection.
(19 Jan 1998) |
oncofetal marker |
A tumour marker produced by tumour tissue and by foetal tissue of the same type as the tumour, but not by normal adult tissue from which the tumour arises.
(05 Mar 2000) |