what is a mutation ?
a change in the DNA base sequence
when does a mutation occur ?
it occurs during DNA replication (interphase)
what are the 6 gene mutations ?
substitution- swapped
deletion- deleted
addition- added
duplication- repeats
inversion- reversed
translocation- removed to the same or another chromosome
what is the impact of gene mutations on proteins ?
DNA base sequence- mRNA codons- amino acid sequence- ionic/H/disulphide bonds- tertiary structure
what does the term degenerate mean ?
more than one triplet/codon codes for the same amino acids in the amino acid sequence
what are the three reasons why mutations may have no effect ?
degenerate, same bonds or introns
what is a frame shift ?
a shift in all base triplets that follow all codons after the mutation will be affected
what does a change in the amino acid sequence do ?
may affect the location of hydrogen/ionic/disulphide bonds between R groups
changes the tertiary structure of the protein
may create a non functional protein
can a mutation have a positive effect ?
creates a new beneficial allele
alleles gives individual a selective advantage to a selection pressure
increased chance of survival
increased chance of allele being passed to offspring
increased frequency of allele
how is the mutation rate increased ?
mutagenic agents
base analogs: can substitute for a base
altering bases
altering the DNA structure
what are some examples of mutagenic agents ?
- ionising radiation
- some viruses e.x HPV Heb B
