Chapter Seven Test three Flashcards
what counts as germinal mutations
point mutations
what is a point mutation
affects one gene
what are examples of point mutations
substitution
deletion
insertion
what counts as a somatic mutation
mosaicism
cancer
what is mutation rate
the probability with which a particular mutational event takes place per biological entity per reproductive cycle
what are substitution mutations
base replaced by other three bases
what are the two types of substitutions
transitions and transversions
what is a transition mutation
purine replace purine
pyrimidine replace pyrimidine
what is a transversion mutation
purine change to pyrimidine or vice versa
who discovered that x-rays are mutagenic
HJ muller
how did muller show x rays are mutagenic
marker chromosome from female mated with male affected by x ray
express gametes
what is a forward muation
wild type allele changed to different allele (recessive or dominant to w+)
what is a reverse mutation
mutant allele to wild type
aka reversion
what is a deletion mutation
block of one or more nucleotides lost from DNA
what is an insertion mutation
addition of one or more nucleotides
what are the mutations rate for spontaneous mutations
very low rate
20 to 43 new nucleotide changes per gamete per cell generations in humans
which genes have better chance of mutation
larger genes
do eukaryotes or prokaryotes mutate more
eukaryotes due to more cell division
is reversion or forward mutation more frequent
forward
sperm or oogenes more susceptible to mutations
sperm bc of more cell division
what does hydrolysis do to a purine
depurination
occurs 1000 times an hour in every cell
create apurinic site, putting random base to compliment
what is deamination
removes NH2 group
changing C to U
inducing a substitution to an A-T base pair after replication
what do X rays do to nucleotides
break DNA backbone
what does UV light do to nucleotides
produce thymine dimers
what does oxidation do to nucleotides
damages individual bases, mispairing
how do you fix a mutation in DNA
excise mutated area with endonucleases
use DNA pol to add new nucleotides and ligase attaches
what enzyme is needed to excise mutated nucleotides
endonucleases
what did Garrod recognize with mutations
enzyme present shows wildtype
enzyme not present then mutations
if enzyme not present for phenylalanine then
phenylketonuria
PKU
if enzyme not present for tyrosine
albinism
if enzyme not present for homogentisic acid
alkaptonuria
what did luria and delbruck discover
bacterial resistance arises from mutations that exist before exposure to bacteriophage
what is the replica plating technique
invert master plate on velvet, invert velvet on new plate, incubate plate, look to see what grows, only penicillin resistant grows and compare to original plate
mutations already occur
what is an auxotroph
need nutrients that were not there
Met-
what is a prototroph
dont need additional nutrients
Met+
what happens to mutated prototrophs
lead to nutritional deficiencies
one gene one…
polypeptide hypothesis
