Transposable Elements Move in Genome + can Create Mutations Flashcards
what are transposable elements
DNA sequences that can move within + between chromosomes inserting into various areas in genome (jumping genes)
what good things might TE do to the genome
help modify + reshape it
what bad things might TE movement cause
mutations, disrupt genes, chm damage e.g double strand breaks
2 groups of transposable elements
retrotransposons
DNA transposons
what do DNA transposons do
move places without going through an RNA intermediate stage
what are located on each transposable elements end
inverted terminal repeats (ITRs)
what codes for transposase enzyme
open reading frame
what are both needed for movement around genome
inverted terminal repeats
open reading frame
what are ITRs recognised and bound by
transposase enzyme
what are made due to TE insertion process
direct repeats
2 things DNA transposons are
autonomous
non-autonomous
how can autonomous transposons move by themselves
as they encode a transposase and have intact inverted terminal repeats
why can’t non-autonous transposons move alone
don’t encode their own transposase enzyme, they need autonomous transposon in genome to use theirs
what mechanisms do most DNA transposons use when moving in genome
cut and paste mechanisms (transposon gene gets cut out of genome and inserted into new position in same/diff ch)
what allows release of transposon, which stays bound by transposase
transposase enzyme binding to TE ends, making cuts between transposon DNA and chm DNA
what does transposase do, before inserting transposon into new place
makes staggered cuts in chm DNA, leaving 5 and 3’ single-stranded DNA overhangs.
what do retrotransposons use as an intermediate to amplify and move within genome
RNA
what do retrotransposons resemble in ways, as they replicate too using similar mechanisms
retroviruses
why aren’t retrotransposons infective, unlike retroviruses
as they don’t encode all proteins needed to form mature viruses
which transposons are more common (39% more) in human genome
retrotransposons
2 types of retrotransposons which can be autonomous/ non-autonomous
long terminal repeats (LTRs)
non-LTRs
what transcribes retrotransposons DNA into 1/more RNA copies in first step of process
cell’s RNA polymerase
2 enzymes needed in retrotransposon process
reverse trascriptase
integrase
what does reverse transcriptase do to RNAs
converts them to double-stranded
what does integrate do when it recognises double-stranded DNA ends
inserts retrotransposons back into genome
what may retrotransposons do at many genome sites
create mutations
