Birgid Schlindwein's
Hypermedia Glossary Of Genetic Terms
Search Results
Birgid Schlindwein'sHypermedia Glossary Of Genetic TermsSearch Results |
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| 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. |
| Base pair (bp) | Two nitrogenous (purine or pyrimidine) bases (adenine and thymine or guanine and cytosine) held together by weak hydrogen bonds. Two strands of DNA are held together in the shape of a double helix by the bonds between base pairs. The number of base pairs is often used as a measure of length of a DNA segment, eg 500 bp. |
| Inverted repeat (IR) | Nucleotide with opposite orientation of the base sequence and mostly below 50 base pairs. IRs are components of IS elements. |
| Transposase | Class of proteins responsible for transposition. One function is to prepare insertion by cutting at the integration site. |
| 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. |