Medical Dictionary Definitions A-Z List
Medical Dictionary Definitions A - Z - «G»:
Gene amplification: Making multiple copies of a gene. Repeated copying of a gene.
Gene amplification plays a role in cancer cells. A tumor cell amplifies, or copies, DNA segments as a result of cell signals and sometimes environmental events.
Amplification can occur in vivo (in the living individ...
Gene array analysis
Gene array analysis: A way of analyzing the differential expression of thousands of species of mRNA (messenger RNA) at the same time in two different samples (as, for example, in normal vs. tumor tissue, or at different developmental stages). Gene array analysis involves synthesizing labeled cDNA (c...
Gene deletion: The total loss (or absence) of a gene. Gene
deletion plays a role in birth defects and in the development of cancer. ...
Gene duplication: An extra copy of a gene. Gene duplication is a key mechanism in evolution. Once a gene is duplicated, the identical genes can undergo changes and diverge to create two different genes.
A duplication is the opposite of a deletion.
Duplications typically arise from an event termed un...
Gene expression: The translation of information encoded in a gene into protein or RNA. Expressed genes include genes that are transcribed into messenger RNA (mRNA) and then translated into protein, as well as genes that are transcribed into types of RNA such as transfer RNA (tRNA) and ribosomal RNA ...
Gene family: A group of genes related in structure and often in function. The genes belonging to a gene family are descended from an ancestral gene.
For example, the hemoglobin genes of critical importance to red blood cells belong to one gene family created by gene duplication (making extra copie...
Gene mapping: The process of determining the relative positions of genes on a chromosome (or another piece of DNA) and the distances between the genes in linkage units or in physical units....
Gene markers: Detectable genetic traits or distinctive segments
of DNA that serve as landmarks for a target gene. Markers are on the same chromosome as
the target gene. They must be near enough to the target gene to be genetically linked to
it: to be inherited usually together with that gene, and so...
Gene pool: The sum total of genes, with all their variations, possessed by a particular species at a particular time....
Gene product: The RNA or protein that results from the
expression of a gene. The amount of gene product is a measure of the degree of gene
Gene silencing: A mechanism by which cells shut down large sections of chromosomal DNA. Gene silencing is done by incorporating the DNA to be silenced into a form of DNA called heterochromatin that is already silent.
The process of gene silencing is important for the differentiation of many differe...
Gene testing: Testing a sample of blood (or another fluid or
tissue) for evidence of a gene. The evidence can be biochemical, chromosomal, or genetic.
The aim is to learn whether a gene for a disease is present or absent. ...
Gene transfer: The insertion of unrelated genetic information in the form of DNA into cells.
There are different reasons to do gene transfer. Perhaps foremost among these reasons is the treatment of diseases using gene transfer to supply patients with therapeutic genes. There are also different way...
Gene, candidate: Any gene thought likely to cause a disease. The gene may be a candidate because it is located in a particular chromosome region suspected of being involved in the disease or its protein product may suggest that it could be the disease gene in question....
Gene, evolutionarily conserved
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....