Mutation

Question 1

what is a mutant

Answer 1

organism in which base sequence of DNA has been changed

Question 2

what is mutation

Answer 2

a heritable change in DNA sequence

Question 3

what is reversion

Answer 3

restoration of original phenotype from a mutant

Question 4

what are consequences of mutations

Answer 4

mutations alter phenotype and disrupt protein function

Question 5

what do mutations do which makes a mutant

Answer 5

they change protein structure which can change and alter the functionality of the protein

Question 6

what are silent mutations

Answer 6

mutations that cause no affect to the protein structure or activity

Question 7

what is a leaky mutation

Answer 7

mutation that has some degree of affect on protein structure or activity
ie. protein functionality may be less efficient at its function that before

Question 8

what are non conditional mutations

Answer 8

mutations that are expressed regardless of the environment

Question 9

what are conditional mutations

Answer 9

mutations expressed under certain conditions
- temperature, suppressor sensitive, or auxotrophic environments

Question 10

what are point mutations, are they leaky, are they subject to reversions

Answer 10

a change in base pair (single, double, or triple)
- can cause missense, nonsense mutation

can be leaky and revert

Question 11

what are deletion mutation, are they leaky, are they subject to reversions

Answer 11

removal of a DNA sequence/ bp
not leaky and cannot revert

Question 12

what are insertion mutations, are they leaky, are they subject to reversions

Answer 12

additional of new DNA, can revert but is not leaky

Question 13

what are inversion mutations, are they leaky, are they subject to reversions

Answer 13

inversion of existing DNA sequence
not leaky and can be reverted

Question 14

what are frameshift mutations, are they leaky, are they subject to reversions

Answer 14

addition or deletion of base pairs not = to a multiple of 3
can be reverted but not leaky

Question 15

what are transversion mutations

Answer 15

pyrimidine changes to purine or vice versa

Question 16

what are transition mutations

Answer 16

when pu–>pu or pyr–>pyr

Question 17

what is a nonsense mutation

Answer 17

when there is a change in a base pair that encodes for a stop codon

Question 18

what is a missense mutation

Answer 18

change in base pair that leads to encoding of different amino acid

Question 19

what is frameshift mutation

Answer 19

addition or deletion of base pairs that causes a shift in the reading frame which encodes for a series of different amino acids downstream

Question 20

what is the lederberg & lederberg experiment studying for, what are the conclusions

Answer 20

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

Question 21

define mutation rate

Answer 21

the probability with which a gene will be mutated in a single generation

Question 22

what are mutation rates dependent on

Answer 22

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)

Question 23

what are 3 mechanisms of spontaneous mutations

Answer 23

1) replication errors
2) alteration of nucleotides
3) recombination

Question 24

what is a tautomer

Answer 24

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

Question 25

what type of mutation do tautomer’s produce

Answer 25

transition mutations

Question 26

how do tautomers escape repair mechanisms

Answer 26

• since they are technically correct, they often evade proofreading functions
• mismatch repair systems can only solve tautomers in they are on an unmethylated daughter strand

Question 27

what is slip strand mispairing

Answer 27

occurs when there is more than one repeated sequence of base pairs on DNA strand.
this causes one of the sequences to pair to another sequence, leaving a loop that would be excised and deleted.

causes frameshift mutations

Question 28

what is deamination

Answer 28

removal of an amine group that leads to another amino acid

Question 29

explain deamination of cytosine to uracil

Answer 29

Cytosine (undergoing hydrolysis) → becomes uracil
Repaired by uracil - n-glycosylase (repair mech that removes amino group)

Question 30

explain deamination of MeC (methylated cytosine) to Thymine

Answer 30

Deamination of 5meC produces thymine, which is not recognized by uracil glycosylase and consequently can result in C → T mutations/ mutation hot spot

Question 31

explain recombination mutations

Answer 31

1) recombination between direct repeats can lead to deletions
2) recombination with inverted repeats can lead to inversions

Question 32

what type of mutagens types are there

Answer 32

1) base analog mutations
2) chemical mutagens
3) intercalating agents
4) mutator genes

Question 33

what are intercalating agents

Answer 33

A substance that inserts itself into the DNA structure of a cell and binds to the DNA

leads to frameshift mutation and DNA damage

Question 34

c