Transposition, genetics
The ability of genes to change position on chromosomes, a process in which a transposable element is removed from one site and inserted into a second site in the DNA. Genetic transposition was the first type of genetic instability to be discovered.
This remarkable phenomenon was discovered by the great American geneticist Barbara McClintock (1902-1992) who won the 1983 Nobel Prize in Physiology or Medicine “for her discovery of mobile genetic elements.” McClintock did her pioneering research in a plant (maize) decades earlier, at a time when the genetic code and the structure of the DNA double helix were not yet known. This type of element has now been found in microorganisms, insects, animals and man and has been demonstrated to have important functions.
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- Transposon
A short mobile DNA sequence that can replicate and of which copies can be inserted at random sites within chromosomes. A transposon has almost identical sequences at each end and inverted repeat sequences (that run in the opposite direction). It codes for the enzyme, transposase, that catalyses its insert in the chromosome.
- Transsexual
A person who desires or has achieved transsexualism.
- Transsexualism
Consistently strong desire to change one’s anatomical gender. Some transsexuals were misassigned gender at birth (for example, being anatomically male but raised as female), either on purpose or due to indistinct anatomy. Most, however, are perfectly normal physically. Transsexuals may dress and behave as individuals of the opposite sex, and they may choose to use […]
- Transthyretin
A plasma protein consisting of 127 amino acids that binds retinol and thyroxine. The gene TTR that encodes transthyretin is in chromosome region 18q11.2-q12.1. Many distinct forms of amyloidosis have been related to different point mutations in TTR. Transthyretin is also called prealbumin (because it migrates faster than albumin in an acidic starch gel).
- Transudate
A fluid that passes through a membrane, which filters out all the cells and much of the protein, yielding a watery solution. A transudate is a filtrate of blood. It is due to increased pressure in the veins and capillaries that forces fluid through the vessel walls or to a low level of protein in […]