Tags & Description
mutation
permanent change of DNA that is heritable
what do mutations do for the gene pool
create allelic variation in the gene pool
do mutations always affect phenotype
no
are mutations always good
no sometimes they are detrimental to the organism and sometimes they have no effect on the organism
point mutations
change of a single nucleotide
what are the different ways a point mutation happens
addition of a base, deletion of a base, base substitution
transition
pyrimidine switched for another pyrimidine, purine for another purine
transversion
pyrimidine switched for purine, purine for pyrimidine
what type of point mutation is more common
transition because polymerase wants the structure to be as close as possible to what its supposed to be
can addition and deletion of multiple bases happen
yes
what effect do base substitution, additions and deletions have on protein function
can have very little if one amino acid is changed, but if the reading frame is changed the entire protein is altered and it can have a huge effect on protein function
silent mutations
do NOT alter amino acid sequence; because genetic code is degenerate
missense mutations
result in change in amino acid
what type of amino acid is considered neutral
nonpolar amino acids
what does a neutral amino acid mean
it does not affect protein function
what type of amino acid change is more likely to change protein function
change from a polar to nonpolar molecule, protein might not fold correctly, be in wrong conformation
in the case of a point mutation where an amino acid is changed from glutamic acid to valine why does it affect cell structure
because glutamic acid is a polar amino acid and valine is a nonpolar amino acid
nonsense mutations
codon for amino acid changed to a stop codon; causes translation to stop and can greatly affect protein structure depending on where the stop codon is in relation to the end of the chain
frameshift mutations
shift reading frame, different amino acid sequence altogether
wild type
prevalent genotype, phenotype in natural population
mutant allele
rare mutation within a population
reversion mutation/ suppressor mutation
a mutation that changes a mutant allele back to wild-type, 2nd site mutations that affect expression of the first mutation
deleterious mutation
decreases chances of survival/ reproduction
lethal mutation
results in death of an organism; mutations on important genes
beneficial mutation
enhances survival and reproduction of an organism
conditional mutation
phenotype only affected under certain conditions
intragenic suppressor mutation
the 2nd mutation site within the same gene as the first
intergenic suppressor mutation
2nd mutation site in a different gene than the first
intergenic suppressor redundant function
1st mutation inhibits function, 2nd mutation alters protein to carry out function, loss of function mutation compensated for by gain-of-function mutation
intergenic suppressor common pathway
proteins function in the same pathway, 1st mutation causes defect in enzyme 1 that slows catalysis, 2nd mutation alters enzyme 2 to increase function
intergenic suppressor multimeric protein
each subunit of multimeric protein encoded by different gene, 1st mutation occurs in gene for one subunit that inhibits function, 2nd mutation in gene for different subunit restores function
intergenic suppressor transcription factor
1st mutation causes loss of function, 2nd mutation in gene for transcription activates expression of another gene compensating for the loss of function
germ line cells
give rise to gametes
where do germ-line mutations occur
in sperm or egg or during gametogenesis and all cells of offspring will have this mutation
somatic cells
all cells of the body except germ line cells
somatic mutations
may occur at anytime during development, mutation passed to daughter cells NOT offspring