Mutation Flashcards
what is a mutant
organism in which base sequence of DNA has been changed
what is mutation
a heritable change in DNA sequence
what is reversion
restoration of original phenotype from a mutant
what are consequences of mutations
mutations alter phenotype and disrupt protein function
what do mutations do which makes a mutant
they change protein structure which can change and alter the functionality of the protein
what are silent mutations
mutations that cause no affect to the protein structure or activity
what is a leaky mutation
mutation that has some degree of affect on protein structure or activity
ie. protein functionality may be less efficient at its function that before
what are non conditional mutations
mutations that are expressed regardless of the environment
what are conditional mutations
mutations expressed under certain conditions
- temperature, suppressor sensitive, or auxotrophic environments
what are point mutations, are they leaky, are they subject to reversions
a change in base pair (single, double, or triple)
- can cause missense, nonsense mutation
can be leaky and revert
what are deletion mutation, are they leaky, are they subject to reversions
removal of a DNA sequence/ bp
not leaky and cannot revert
what are insertion mutations, are they leaky, are they subject to reversions
additional of new DNA, can revert but is not leaky
what are inversion mutations, are they leaky, are they subject to reversions
inversion of existing DNA sequence
not leaky and can be reverted
what are frameshift mutations, are they leaky, are they subject to reversions
addition or deletion of base pairs not = to a multiple of 3
can be reverted but not leaky
what are transversion mutations
pyrimidine changes to purine or vice versa
what are transition mutations
when pu–>pu or pyr–>pyr
what is a nonsense mutation
when there is a change in a base pair that encodes for a stop codon
what is a missense mutation
change in base pair that leads to encoding of different amino acid
what is frameshift mutation
addition or deletion of base pairs that causes a shift in the reading frame which encodes for a series of different amino acids downstream
what is the lederberg & lederberg experiment studying for, what are the conclusions
studying to see if mutations were random or if they only occurred in response to stressors
plated e-coli with T1 resistant mutation, mutated colonies formed in same spots of every replicate prior to introduction of T1 phage (stressor)
concludes that mutation is spontaneous and random, does not require stressor
define mutation rate
the probability with which a gene will be mutated in a single generation
what are mutation rates dependent on
1) gene size (short genes mutate less)
2) nucleotide sequences (spots that are susceptible to mutation i.e. those with 2 h-bonds may mutate more than those with 3-h-bonds)
3) number of genes that dictate a phenotype (ie. if one phenotype depends on a large sequence of genes, it will likely be victim to mutation)
what are 3 mechanisms of spontaneous mutations
1) replication errors
2) alteration of nucleotides
3) recombination
what is a tautomer
an alternate form of bases with altered base pairing properties
ie) change in structure of adenine (now A-enol) may cause a pair with cytosine instead of thymine, thus, during polymerization adenine will call for thymine but now cytosine will call for guanine when it should have been thymine calling for adenine
