Lecture 19

Question 1

mutation

Answer 1

a heritable change in genetic information

includes cell lines (somatic mutations), viruses, and organisms (germ-line mutations)

Question 2

somatic mutation

Answer 2

occurs in a single body cell and cannot be inherited

mutant cell goes through mitosis

Question 3

germ-line mutation

Answer 3

occurs in gametes and can be passed on to offspring

goes through sexual reproduction

Question 4

three basic types of mutations

Answer 4

base substitution - one codon is changed
base insertion - codon is added
base deletion - codon is removed

Question 5

frameshift mutations

Answer 5

if multiples of three are removed or added, in-frame insertion/deletions are created, causing a shift

Question 6

expanding trinucleotide repeats

Answer 6

represent a common type of 3 base insertion

Question 7

expansion of trinucleotide within a coding sequence…

Answer 7

results in incorporation of extra copies of a single amino acid

Question 8

expansion outside a coding sequence…

Answer 8

causes dysfunction by unknown mechanisms

Question 9

base substitution: transitions

Answer 9

substitution of a purine for a purine, or a pyrimidine for a pyrimidine
more common

Question 10

base substitution: transversions

Answer 10

substitution of a pyrimidine for a purine, or a purine for a pyrimidine

Question 11

purines vs pyrimidines

Answer 11

A and G are purine

T, and C (U) are pyrimidine

Question 12

anticipation

Answer 12

increase in the severity of a disease over subsequent generations. occurs when adding more trinucleotide repeats than needed.

Question 13

fragile X chromosome

Answer 13

associated with a characteristic constriction of the long arm.

Question 14

the more trinucleotide repeats you have…

Answer 14

the more hairpin structures that develop since replication is more likely to be increased

Question 15

missense mutations

Answer 15

a mistake in the DNA resulting in the wrong amino acid being incorporated into the protein

Question 16

nonsense mutations

Answer 16

mistake of incorporating a stop codon

Question 17

silent mutations

Answer 17

doesn’t cause a significant change in the amino acid

Question 18

forward mutation

Answer 18

changes the genotype and phenotype of an organism

Question 19

reverse mutation

Answer 19

goes back in the opposite direction of a forward mutation

Question 20

suppressor mutation

Answer 20

surpasses both forward and reverse mutations

it has its own genotype, but the phenotype is usually the same

Question 21

intragenic suppressor mutation

Answer 21

occurs in the gene that has the mutation

Question 22

intergenic suppressor mutation

Answer 22

occurs on a gene other than the one with the original mutation

Question 23

mutation rates

Answer 23

the frequency of change of a wild-type allele to a mutant one
rates can be expressed per cell, per gamete, etc
factors effecting calculation are frequency of change, rate of repair, and probability of detection

Question 24

cause of mutations

Answer 24

may be spontaneous or induced

Question 25

spontaneous mutations

Answer 25

replication errors, tautomeric base forms, flexibility of the DNA structure, spontaneous chemical changes

Question 26

induced mutations

Answer 26

chemicals and radiation

Question 27

tautomeric shift

Answer 27

when a proton changes its position, resulting in a tautomeric form
different DNA bases will resemble an original base pair

Question 28

wobble base pairing

Answer 28

can lead to a replicated error

Question 29

incorporated errors

Answer 29

occur when a mismatched base is incorporated into a newly synthesized strand

Question 30

replicated errors

Answer 30

occur when the incorporated error is replicated so the mutation exists on both strands

Question 31

strand slippage and unequal crossing over

Answer 31

leads to insertions or deletions

Question 32

depurination

Answer 32

the loss of a purine base from a nucleotide

produces an apurinic site, opening up more spaces for mutations to happen

Question 33

deamination

Answer 33

when you remove an amino group from a molecule

alters DNA bases, leading to a mutation

Question 34

base analogs

Answer 34

resemble normal bases but are mismatched at higher frequency
may become incorporated and replicated errors

Question 35

reactive oxygen

Answer 35

often leads to oxidative damage to DNA

Question 36

intercalating agents

Answer 36

can insert or delete themselves, causing a mutation in the DNA base pair

Question 37

pyrimidine dimers

Answer 37

mutation as a result of ultraviolet light

Question 38

transposable elements

Answer 38

can cause a mutation by inserting into genes, or disrupt them by removing themselves

Question 39

ames test

Answer 39

used to measure mutagenesis

uses bacteria to test whether a given chemical can cause a mutation

Question 40

mismatch repair mechanism

Answer 40

repairs replication errors like mis-paired bases and strand slippage
changes nucleotides back to original structure

Question 41

base excision repair

Answer 41

repairs abnormal bases, modified bases, and pyrimidine dimers
excises modified bases and replaces entire nucleotide together

Question 42

trans-lesion DNA polymerases

Answer 42

gives the cell additional time to repair damage before it’s replicated
an error prone type of repair