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Flashcards in Mutagens & Mutations Deck (26)
1

what is a free radical

unstable molecule with an unpaired outer electron

fragments of broken biomolecules

2

how do free radicals come to be?

normal metabolism

inflammation

UV light/ionizing radiation

tobacco smoke, pollutants in air/water

3

ROS

reactive oxygen species

4

how do we deal with free radicals?

cells have enzyme detox systems

convert oxygen free radicals into O2 + water

5

mutagenic chemicals

attack DNA specifically

moldy peanuts fungal toxin: aflatoxin

sulfur mustard

6

mutagenic chemicals used to create new mutations

ethylnitrosourea and ethylmethanesulfonate

react with bases to cause lesions

could be used to kill dividing cancer cells in chemo

7

two kidns of electromagnetic radiation that affect DNA

UV: base dimers

ionizing: xray/gamma ray

8

particulate radiation

strongly ionizing

inhalation of radioactive radon gas (55%)

basements cut from solid rock accumulate radon

9

chemicals in food

dark meat is a source of carcinogens

processed meat that has preservatives/nitrates

childhood leukemia (hotdogs)

10

5 effects of a mutation inside an ORF

silent

missense

nonsense

codon gain/loss

frameshift

11

point mutations cause what kind of effects

silent

missense

nonsense

12

silent mutation

point mutation that does not change the meaning of a codon (no coding change)

13

missense mutation

point mutation that change one amino acid to another

coding change

14

nonsense mutation

point mutation that turns an amino acid codon into a stop codon

18 codons are 1 base away from stop

15

which two mutation effects are caused by insertions or deletions?

codon gain/loss and frameshift

in frame: deletion/insertion of 3 bases causes codon gain/loss

frameshift: deletion/insertion of anything other than 3 bases

16

codon gain/loss

inserts or deletes 3 nucleotide bases (1 aa)

17

frameshift

changes all downstream codons and causes a new termination point

can cause a protein of any length

18

neutral aa changes

some aa changes and gains/losses do not affect protein function

19

other effects of small mutations

effects: intron splice sites

regulatory sites inside or outside of transcription units

20

effects on intron splice sites

introns begin with GU (RNA)/ GT and end with AG

this is how a splicosome knows where to cut

if mutate either code, might splice wrong bit

21

effect on regulatory site outside of transcription unit

relates to CRM

may affect TF binding site so it doesn't bind, phenotypic effect

22

unequal crossing over and strand slippage produce...

duplicated sequences

unequal crossing over: meiosis

strand slippage: DNA replication

23

variable number tandem repeat VNTR

places in DNA where same short sequence of bases is repeated in multiple tandem copies

variation in individuals btw # of copies

unequal crossing over in meiosis requires a recombination at the VNTR site

24

are VNTR sites protein coding?

no, function is not clear

25

DNA fingerprinting

VNTR genotypes are the basis b/c differ in each individual

26

triplet repeat expansions

a set of genetic diseases where expansion multiplies repeats within a gene

DNA replication

repeats can be in an ORF or UTR