Lecture 12: Dynamic Genomes, Transposons, and Complex Traits Flashcards
What is a transposon?
(Also called transposable element).
A discrete DNA sequence element that can move from one location in the genome to another often under the control of a transposase encoded by the element itself.
What is truncated mRNA?
When the sequencing reaction is terminated prematurely, resulting in a partial sequence of the DNA fragment.
What is transposon mutagenesis?
Exploiting natural transposons to generate insertions mutants.
What are flanking direct repeat sequences?
Flanking (or terminal) repeats (terminal repeat sequences) are sequences that are repeated on both ends of a sequence.
What are the two ways DNA transposons move?
- Replicative transposition – copied to a new location.
• Conservative transposition – the transposon is completely removed from the genome and reintegrated into a new, non-homologous locus, the same genetic sequence is conserved throughout the entire process.
+ In replicative transposition, a transposable element is duplicated from the part of donor DNA.
On the other hand, in nonreplicative transposition, the element form donor DNA moves directly to recipient DNA.
Who discovered transposons?
Barbara McClintock.
She received a Novel Prize for Physiology or Medicine in 1983: “for her discovery of mobile genetic elements”.
What is the Ac transposable controlling element?
Activator.
Ac elements are autonomous and their movement results in a 4.3 kb insertion.
They alter the regulation of gene expression and may create unstable insertion alleles, stable derivatives, or excision alleles due to insertion of a transposable element into a gene.
A full-length Ac element contains a functional transposase gene.
What is the Dc transposable controlling element?
Dissociation.
Ds elements are not autonomous because they cannot produce the transposase needed for transposition, and can only transpose when it is provided by the Ac element.
The Ds element has an internal deletion and does not code for a functional transposase.
What does transposase do for Ac/Dc?
Recognises the 11 bp inverted repeats (IRs) at either end of the Ac & Ds transposons and catalyses the transposition of both Ac and Ds elements.
What can recombination between transposon pairs result in?
Deletion of segments of the genome or chromosome breaks.
