Lecture 3/12 Flashcards
where will one find a protein that affects the protein activity, and is that a quantity or quality issue?
they MUST be inside the protein coding region; quality issue
what are examples of mutations that can affect protein quality
nonsense, missense, frameshift, deletions
where would you find mutations that affect the protein levels and is this a quality or quantity issue?
outside of the protein coding region; quantity issue
what kinds of mutations can be found outside of the protein coding region?
point, deletion, substitution
what kinds of mutations can not be found outside of the protein coding region?
nonsense, missense, frameshift
what does it mean to be a hypermorphic mutation
it is a gain of function mutation that either makes more protein of a more efficient protein
what kind of mutation can be a hypermorphic mutation?
any
would a hypermorphic be found inside or outside the protein coding region? hypomorphic?
either can be found inside or outside the protein coding region
what is considered to be the regulatory region?
5’ and 3’ UTR, outside of the protein coding region
where is the promoter in relation to the protein coding region?
it is upstream of the initiator codon
where is the promoter in relation to the regulatory region?
it is in the regulatory region
what happens in a missense mutation?
one amino acid is replaced for another
if there is a mutation between the promoter and the AUG, what region is that considered?
the 5’ UTR
what does a forward mutation do?
changes WT allele to a different allele
what does a reverse mutation/reversion do?
changes a mutant allele back to WT
what does it mean to be an intragenic suppressor?
a second mutation in the same gene that reverts the effects of a mutation back to WT
which rate is usually higher: forward mutation or reversion?
forward mutation
what is a compensatory mutation?
restore or improve the effects of another mutation, often back to WT
what is the calculation for determining spontaneous rates of mutation?
how many you see (# of mutations) divided by # of gametes tested (haploid)
is spontaneous mutation rate calculated with diploid genome or haploid?
haploid
what affects mutation rates?
differences in gene size and susceptibility to various mutagenic mechanisms (ie. if it’s in a hotspot for mutation)
if a gene is bigger, is it more or less likely to mutate?
more likely
is mutation rate in gamete-producing euks higher or lower than proks? why?
higher bc euk genome is bigger and there are more cell divisions bt zygote formation and meiosis in germ cells
who tolerates mutations better, diploid or haploid organisms?
diploid bc generally mutations are recessive and you could still have WT function from one allele
are bacteria diploid or haploid?
haploid
what are the two hypotheses for why bacteria can be resistant to antibiotics? which is correct
they are exposed and therefore mutate in response, or they already have the mutations; the second hypothesis is correct
what did the penicillin/bacteria experiment show? how?
that bacterial resistance is the result of preexisting mutations – we can see this because of 3 triplicate plates where bacteria grow on a medium with penicillin and the bacteria that survive are always in the same spots. if the bacteria grew resistant as a result of exposure, the bacteria would grow randomly on the plate
how do antibiotics work?
they disrupt a pore used for transport
once mutations in bacteria (to make them resistant) occur, are those mutations stable or unstable?
they usually remain stable
are mutations that occur in replication rare or common?
rare
what do our bodies make in naturally occurring mutations?
free radicals (super oxide O2-) and hydrogen peroxide H2O2
what cellular processes make free radicals and hydrogen peroxide?
oxidative phosphorylation, NADPH oxidase, and 5-lipoxgenase
what are two enzymes that get rid of the free radicals and hydrogen peroxide
superoxide dismutase (ROS = reactive oxygen species) and catalase
what can a superoxide do to an individual base?
it oxidizes it, causing oxidative damage and the potential to mispair after replication (the other strand would be fine)
what kind of mutation occurs from an ROS?
point mutation
what is a depurination?
removal of a purine (either A or G) by heat or acid and that apurinic site will randomly pair with another nucleotide
which happens more often, depurination (A and G) or depyrimidination (C and T)?
depurination
what happens in deamination of C?
the amino group is ripped off of C and replaced by an oxygen, making the look like a U, so it will pair with an A
what kind of mutation is caused by deamination of C?
point mutation
What do X-rays do to DNA?
they break the sugar-phosphate backbone, causing a double-stranded break
what happens to the double stranded break from X-rays?
the strands are ligated back together, causing a deletion
what does UV light cause to happen in DNA?
adjacent Ts will create a thymine dimer, causing abnormal pairing
what happens at high intensity UV?
double-stranded breaks
what does a hydroxylating agent do?
adds an OH group
what do hydroxylating agents do to DNA
if they add an OH group to a C, it will make it look like a T and then it will pair with an A
what do alkylating agents do?
add an ethyl or methyl group
what happens when you add an ethyl group to a G?
If you add an ethyl group to a G, it looks like an A and will pair with a T
what are transposable elements?
elements that move around the genome; they can jump into a gene and disrupt its function
what are the two mechanisms of transposon movement?
Duplicates itself, excises and inserts itself elsewhere OR the transposon excises itself and randomly goes to another area
there are repeats of CGG at the end of the FMR1 gene, what does that cause to happen?
there’s a lot of slippage, causing it to keep getting replicated. you can end up with a damaging (fragile X) or non-damaging number of copies, it can also get twisted into a loop out
what shape represents women in a pedigree?
circle
what shape represents men in a pedigree?
squares
what did muller find about drosophila in terms of x ray mutation
X rays can cause mutations, if F1 female has X-ray induced mutation, only males that survived had bar eyes
