gene mutations Flashcards
what is a gene mutation?
alteration to a base in a sequence of bases of a single gene
mutagenic agents
gene mutations are spontaneous but the frequency of them occuring is increased by factors called mutagenic agents.
when are mutations most likely to occur?
during DNA replication during interphase
how do mutations affect the tertiary structure?
alters primary structure/specific sequence of amino acids that encodes the polypeptide.
this alters the tertiary structure as the hydrogen, ionic and disulfide bonds form in different places.
results in a non functional protein.
how can mutations result in cancer?
alterations to the gene can resutl in a mutation that causes cancer.
mutagenic agents
high energy ionising radiation
alpha and beta particles
x rays
gamma rays
UV light is not ionising but is still high enough to cause damage and disrupt the structure of DNA.
carcinogens- chemicals that can alter the structure of DNA and affect transcription. Includes mustard gas, peroxides and tobbaco smoke.
what are the 6 types of gene mutations?
addition
deletion
substitution
inversion
duplication
translocation
addition
one base is added to the sequence of bases
causes a frame shift to the right
can be very harmful as codons may code for different amino acids so alters the primary structure of the protein
can reuslt in formation of non functional protein.
deletion
deletion of base from sequence
results in frame shift to left
alters polyppetide chain and formation of non functional protein.
substitution
one base is replaced by another base
there is no change in the number of bases and no frame shift
due to only one codon being changed and the genetic code being degenerate, this may result in the same amino acid and have no impact
inversion
a section of bases detaches from the DNA sequence but when they reattach they are inverted
