KA6: mutations Flashcards
what is a mutation?
mutations are changes in dna that can result in no protein or are altered protein being synthesised
what is a single gene point mutation & examples…
involves the alteration to the dna nucleotide sequence as a result of substitution, insertion or deletion of nucleotides
what happens when a missense mutation occurs?
one amino acid is changed for another = non functional protein or have little effect on the protein
during nonsense mutation what happens?
the substituted nucleotide results in a premature stop codon = shorter protein
during nonsense mutation what happens?
the substituted nucleotide results in a premature stop codon = shorter protein
what happens during splice site mutations?
some introns are retained and/ or some exons are not included in the mature transcript
“stop this nonsense”
results in a premature stop codon
what kind of mutations result in a frame shift mutation?
insertion ajd deletion
what happens during frame shift mutation and what effect does it have?
they cause all of the codons and all the amino acids after the mutation to be changed .
has a major effect on the structure of the protein produced
what do chromosome mutations alter and change?
they alter the structure of the chromosome and change the sequences of genes on the chromosome
what is a deletion (chromosome mutation)?
when a section of the chromosome is removed
what happens during insertion and deletion single gene mutations?
I- an extra nucleotide is added moving all the other nucleotides along.
D- a nucleotide is deleted again moving all the others along.
Both mutations change all amino acids after the mutations
what is a duplication mutation?
a section of chromosome is added from its homologous partner
what occurs during an inversion mutation?
a section of the chromosome is reversed
what occurs during a translocation mutation?
translocation is where a section of chromosome is added to a chromosome, not from its homologous partner
why are chromosome mutations described as being lethal?
because of the substantial changes
what is the importantance of gene duplication & mutations in evolution ?
allows potential beneficial mutations to occur in a duplicated gene whilst the original gene can still be expressed to produce irs protein
