Unstable DNA Repeats Flashcards
What are the different repeats?
Tandem repeats , triplet
Why does having repeating sequences cause problems?
Frameshift of DNA, DNA polymerase can jump the sequence, formation of unstable structures because they’re more susceptible to damage
How is repeats affected over generations
Expansion of repeats gets longer because of of repair and recombination mechanisms
What effects can repeats have generationally?
Expansion or contracting
What’s the effect of longer repeats?
Longer repeats mean more severe symptoms
Where does repeats occur?
Promoter, untranslated regions, introns, coding region generating an aberrant protein
What are result of repeats on promoter?
Transcriptional silencing and loss of function mutations
What are results of repeats in introns
Impaired transcription, loss of protein because less mRNA
What happens when repeats are in the untranslated region?
X
What is fragile X syndrome?
Repeat sequence is CGG
What does FMRP Protein do?(loss of function
RNA binding protein, control local protein synthesis, point mutations
What happens in Huntington’s disease?
HTT gêne on chromosome 4 , expansion of CAG triplet repeat 36 or more repeats cause disease, CAG codes for glutamine, toxin gain of function,
What does the Huntington’s protein affect?
Folding of other protein, mitochondrial dysfunction, blocked protein devrait-on pathways, impaired vesicle transport, calcium signalling impaired.
What is myotonic dystrophy?
Autosomal dominant, multi systemic-disease,
What dues loos if function explain?
X
