Lecture - 21 - Transposable Elements Flashcards
What are transposable elements?
Sequences that can move about the genome
What is Transposition?
Movement of the transposons
What are common features of transposons and how they move?
Short flanking repeats on both ends, regenerated at the point of insertion.
Staggered cuts are made in the target DNA leaving short single-stranded pieces of DNA on either side of the transposon, Replication of single stranded DNA recreates the short flanking repeats.
also contain terminal inverted repeats
How do transposons cause mutations?
Inserting into another gene + promoting DNA rearrangements.
What is Replicative transposition?
“Copy and Paste” transposition. New copy of transposable element inserted at new site and old one stays home.
What are the enzymes involved in replicative transposition?
Transposase and Resolvase
What is Transposase?
Enzyme that binds to the end of a transposon and catalyzes the movement
What is Resolvase?
Enzyme that brings about the separation of two transposons contained in a cointegrate during the process of replicative transposition.
What is Non-replicative transposition?
“Cut and Pase” transposable element is cut from old site and inserted into a new site.
What are Retrotransposons?
Found in Eukaryotes, elements that transpose through an RNA intermediate.
What is the mechanism of Retrotransposons?
RNA is transcribed by DNA transposable element, This RNA is copied back to another DNA site using reverse transcriptase.
Only done through replicative transposition
Which is more common SINEs or LINEs?
LINEs - Long interspersed nuclear elements
Chromosomal rearrangements are a consequence of what?
Transposed sequences.
What was Barbara Mclintocks contribution to genetics?
She discovered transposition and used it to demonstrate that genes are responsible for turning physical characteristics on and off.
New evidence suggests that cancers driven by P53 mutations could represent what?
Transposopathies… disease states linked to eruptions of mobile elements.
When P53 is mutated, retrotransposition greatly increases
