Mutations Flashcards
What is the most common type of SNP?
C to T change
What is a transition SNP?
When 2 bases that are the same size are swapped (eg. 2 purines)
What is a transversion SNP?
Bases that are different sizes are swapped (eg. a purine and a pyrimidine)
What position in a triplet is a SNP unlikely to cause any change?
3rd position (wobble position)
What is a missense mutation?
1 amino acid is substituted by another, normally a SNP
What is a silent mutation?
A single-base mutation which does not substitute the amino acid
What is a non-sense mutation?
An amino acid codon is mutated to a stop codon
What is a frameshift mutation?
The reading frame of the mRNA is altered due to an insertion, a deletion or a premature stop codon.
What is a conservative missense mutation?
Amino acids with similar properties may have no consequence if substituted for each other.
What will happen to the reading frame if 3 bases are inserted or deleted?
Nothing. The reading frame is not disrupted
How are nonsense mutations causing premature termination codons (PTC) degraded?
Nonsense mediated decay (NMD)
List 3 causes of DNA base changes
Sequence changes in DNA replication
Chemicals
Radiation
What is a tautomeric shift?
A proton briefly changes position in a base during replication. This results in altered base-pairing properties and so acts as an altered template in DNA replication.
What occurs in ‘slippage’ during replication?
When there is a run of the same base, in replication, the newly synthesised strand can loop out resulting in the addition of a nucleotide. This causes a frameshift mutation.
How does the mutagen IQ work?
Disrupts the packing of DNA bases and causes single base deletions. It forces the bases further apart
