Set 22: Transposable Elements Transposons, Insertion Sequences, Inverted repeats, retrotransposons and how they work
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Set 22: Transposable Elements
March 28, 2011
Transposable elements: small segments (50-10,000 base
pairs) of DNA that are able to excise themselves and move
from one place to another in the genome “jumping genes”.
-may move, or copy themselves (cut& paste or copy & paste)
“selfish” – carry only information required for their own
Marcus Rhoades & Barbara McClintock did experiments of
transposable elements in corn.
Prokaryotes: carry insertion sequences & transposons, both cut
- have terminal inverted repeats (IR= Inverted Repeat)
- have transposase gene which codes for transposase
- transposase cuts at inverted repeats and cuts the host
DNA for Insertion
- host cell then uses ligase to repair itself
(see slide 7)
- middle codes for transposase gene, but also one or more
other genes (see slide 9)
speckling: transposons moved out of some cells