Unit 02.4: Mutations Flashcards
(27 cards)
how is genetic variation created?
recombination and mutations!
what are germ line mutations? name an example.
mutations that are passed on from one generation to the next.
ex. mendel’s experiments with peas
what are somatic mutations?
can be passed onto subsequent lineage of cells through MITOSIS, but are not heritable from parent organism to daughter organism
what is a synonymous a^2 mutation?
a mutation that changed the amino acid
what is a non-synonymous a^2 mutation?
a mutation that changed the amino acid
what is a missense mutation?
when the change in RNA codon results in a change in a^2
what is a silent mutation?
when the change in RNA codon does not change the amino acid
what is a nonsense mutation?
when the change in RNA codon causes a premature stop
what is a nonstop mutation?
when the change in RNA codon changes a stop codon to an amino acid
what is a transition substitution mutation?
when a nucleotide is exchanged for its same type.
purine -> purine or pyrimidine -> pyrimidine
what is a transversion substitution mutation?
when a nucleotide is substituted for not its same type???
purine -> pyrimidine or vice versa
what is an insertion frame shift mutation?
when a nucleotide is inserted, resulting in everything past the inserted nucleotide moving one bp upstream
what is a deletion frame shift mutation?
when a nucleotide is removed, resulting in everything past the inserted nucleotide moving one bp downstream
what is it called when a non-synonymous mutation results in the change from one amino acid to another but they both have similar chemistries?
conservative mutation
what is it called when a non-synonymous mutation results in the change from one amino acid to another but they both have different chemistries?
non-conservative mutation
how can a counter balance be achieved with a frame shift mutation to restore the open reading frame?
a combination of both an insertion and a deletion at two points within ORF
describe the mutation in the ras gene and its effects.
- missense mutation where position 12 glycine changes to a valine
- glycine and valine are both non polar but have very different side chain structures.
- mutation blocks Raas protein GTPase activity, causing Ras protein to stay in its active form
- active Ras protein results in uncontrollable cell division, leading to cancer
what is the effect of a promoter mutation? what is an example?
affects timing/amount of transcription as it alters consensus sequence.
ex. beta-hemoglobin gene has many promoter mutations resulting in reduction in transcription efficacy resulting in less beta-hemoglobin produced
what is the affect of a polyadenylation mutation?
alters sequence of mRNA as poly-A-tail cannot be brought in
what is the affect of a splice site mutation?
improperly keeps and intron or mistakenly removes exon
what is the affect of a DNA replication mutation?
increases number of short DNA repeats
describe the splicing mutation that occurs in beta-hemoglobin
- normally, an AG is at the 3’ end of the exon, right before the splice site, and a GT is at the 5’ end of the intron, right after the splice site
- changing the first nucleotide to an A/T or the fifth nucleotide to a C results in NO splicing
- while changing the 5th position nucleotide to a T/A or the 6th position nucleotide to a C will reduce the splicing at the site
what is a cryptic splice site? what is the example in beta-hemoglobin?
when a base pair substitution creates a splice site that replace/compete the authentic splice site.
ex. in the beta-hemoglobin gene, intron 1 is 130 bp long. a base pair substitution changes a G to an A at position 110, creating a cryptic splice site, resulting in only 90% of intron 1 being spliced
why are mutation important?
provide genetic variation
