Birgid Schlindwein's
Hypermedia Glossary Of Genetic Terms
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Birgid Schlindwein'sHypermedia Glossary Of Genetic TermsSearch Results |
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| Transposon (Tn) | DNA elements carrying genes for transposition and other genetic functions. The former genes enable those elements to move from one site on a chromosome to another. In many cases the latter genes enable bacteria to live in extreme environments. Transposons are much longer than IS elements. Some resemble, and may originate from, retroviruses.
Also called transposable element or 'jumping gene'. |
| Deoxyribonucleic acid (DNA) | The molecule that encodes genetic information. DNA is a double-stranded molecule held together by weak bonds between base pairs of nucleotides. The four nucleotides in DNA contain the bases: adenine (A), guanine (G), cytosine (C), and thymine (T). In nature, base pairs form only between A and T and between G and C; thus the base sequence of each single strand can be deduced from that of its partner. |
| Gene | The term coined by Johannsen (1909) for the fundamental physical and functional unit of heredity. The word gene was derived from De Vries' term pangen, itself a derivative of the word pangenesis which Darwin (1868) had coined. A gene is an ordered sequence of nucleotides located in a particular position (locus) on a particular chromosome that encodes a specific functional product (the gene product, i.e. a protein or RNA molecule). It includes regions involved in regulation of expression and regions that code for a specific functional product. See gene expression, allele. |
| Transposition | Moving a DNA segment from one position of the genome to another or to a different genome. This change in genome structure happens in many organisms from bacteria to higher plants and animals. Requirements: (1) intact inverted repeats at the ends of the IS-elements or transposons and (2) active transposase Mechanisms
The cut and paste mechanism leaves 'scars' in the donor molecule. Thus genes can be damaged or destroyed. Mutations may be induced via insertions into structure genes. Deletions or inversions may also be the result of a transposition. History: Transposition was discovered by Barbara McClintock in the late 1940ies during her studies on maize genetics ('jumping genes'). 1983 she won the Nobel Prize for her transposon research. See retrotransposon. |
| Chromosome | The term was proposed by Waldeyer (1888) for the individual threads within a cell nucleus (gk. chroma, colour; soma, body). The self-replicating genetic structures of cells containing the cellular DNA that bears in its nucleotide sequence the linear array of genes. In prokaryotes, chromosomal DNA is circular, and the entire genome is carried on one chromosome. Eukaryotic genomes consist of a number of chromosomes whose DNA is associated with different kinds of proteins. |
| Insertion sequence (IS element) | Group of transposable elements that were detected by Saedler, Starling and Shapiro. They constist of 800 to 2000 base pairs and carry inverted repeats at their ends. The central part consists of reading frames and codes for transposases responsible for transposition. |
| Retrovirus | Short for Reverse Transkriptase Onko Virus. RNA virus that encode the enzyme reverse transcriptase so that their RNA can be transcribed into DNA in the host cell; modified retroviruses are used as vectors to introduce genes (or portions thereof) of interest into eukaryotic cells. Siehe weitere Informationen des Instituts für Virologie, VMU Wien (in Deutsch). |