10.3

Question 1

what are the two types of mutations (in terms of transmission?

Answer 1

somatic mutations - not transmitted
germ-line mutations - may be transmitted to ~50% of offspring

Question 2

what are the classifications of point mutations based on aa’s?

Answer 2

silent/synonymous - no change
missense/nonsynonymous - 1 aa changes
nonsense - stop codon

Question 3

what are the classifications of point mutations based on affect on sequence?

Answer 3

indels cause frameshifts that alter reading frames (missense or nonsense) - except when they occur in groups of 3
indels outside of reading frames have no effect

Question 4

what are the classifications of mutations based on functional phenotype?

Answer 4

loss-of-function - recessive inheritence
gene-of-function (new/wrong gene product) - dominant inheritence
neutral

Question 5

what are transitions vs transversions?

Answer 5

transitions - purine/pyrimimide swap
transversions - purine/pyrimimide stay the same

Question 6

do transition or transversion mutations happen more often?

Answer 6

transitions

Question 7

what are forward vs reverse mutations?

Answer 7

forward alters wild phenotype
reverse changes mutant back to wild phenotype

Question 8

what are suppressor mutations?

Answer 8

mutation that suppresses a previous mutation

Question 9

what are the two types of suppressor mutations?

Answer 9

intragenic (same gene)
intergenic (diff gene)

Question 10

how do mutations happen?

Answer 10

spontaneously or induced

Question 11

what are the three types of spontaneous mutations?

Answer 11

tautomeric shifts (of bases) during DNA rep
DNA strand-slippage during DNA rep
misalingment of homo chromosomes during crossing over (recomp) at meiosis I

Question 12

what are tautomeric shifts?

Answer 12

small chemical changes in bases that change which base they can bind to

Question 13

what is DNA slippage?

Answer 13

strands slip into small loops which results in adding/leaving out a nucleotide

Question 14

what are mutagens?

Answer 14

agents that cause mutations:
radiation or chemical mutagens

Question 15

what is ionizing radiation?

Answer 15

dislodges electrons to cause free radicals/ions that alter base structure and break phosphodiester bonds

Question 16

what is ultraviolet radiation?

Answer 16

weaker ionizing radiation
comes from sun
causes pyrimidine dimers that blocks DNA rep

Question 17

how do we repair damaged DNA from UV?

Answer 17

protein recognizes mismatches and unwinds, excises nucleotides, fills in correct nucleotides

Question 18

what is xeroderma pigmentosum?

Answer 18

autosomal recessive genetic disorder where cells cannot repair mutations caused by UV light

Question 19

what are base analogs?

Answer 19

chemical mutagen that look like bases but cause incorrect pairing and point mutations

Question 20

what are base-modifying agents?

Answer 20

chemical mutagens that change bases to pair incorrectly and cause point mutations

Question 21

what are intercalating agents?

Answer 21

chemical mutagen that distort normal base stacking and cause insertion/deletion of a base pair

Question 22

what is the ames test?

Answer 22

method to mutagens by comparing growth reversions of salmonella on different mediums (mutagens will cause growth)

Question 23

what does rat liver enzyme do in the ames test?

Answer 23

mimic chemical modification of potential mutagens in human body (could make chemical more or less mutagenic)