3.8.1 mutations Flashcards
what is a gene mutation?
a change in DNA’s base sequence of chromosomes.
when does a gene mutation occur?
during DNA replication.
what can increase the rate of mutation?
MUTAGENIC AGENTS
- xray.
- radiation.
- chemicals.
- viruses.
what is a substitute gene mutation?
a change of a single base (or more) for a different base.
what type of mutation is substitution?
a point mutation.
what effect does a substitution mutation have?
- may have no effect due to degenerate genetic code = so same amino acid.
- change the amino acid, so it would change the tertiary structure unless the chemical properties are the same.
- introduce a stop codon/triplet and shorten the polypeptide chain.
what is a deletion mutation?
when one or more bases are removed.
what does a deletion mutation cause?
FRAMESHIFT so all base triplets after the mutation are changed, which causes a significant change in tertiary structure. this is because it changes the number of nucleotides in the sequence so it’s not divisible by 3 and due to translation reading in triplets = the protein made is significantly different.
what is an addition mutation?
when one or more bases are added.
what does an addition mutation cause?
FRAMESHIFT so all base triplets after the mutation are changed, which causes a significant change in tertiary structure. this is because it changes the number of nucleotides in the sequence so it’s not divisible by 3 and due to translation reading in triplets = the protein made is significantly different.
what is an inversion mutation?
when a section of DNA is reversed.
what effect does an inversion mutation have?
- changes the triplet in this region so the amino acid produced would be different.
- changes the tertiary structure of the protein.
what is a silent mutation?
no change to amino acid.
what is a nonsense mutation?
produces a STOP codon.
what is a missense mutation?
a change to the amino acid.
