DNA Repair

Question 1

what is a point mutation?

Answer 1

change from one base to another

Question 2

what is a missense mutation?

Answer 2

base change produces a different amino acid

Question 3

what is a nonsense mutation?

Answer 3

base change produces a stop codon

Question 4

what is a transition mutation?

Answer 4

pyrimidine to pyrimidine or purine to purine

Question 5

what is a transversion?

Answer 5

purine and pyrimidine interchanged

Question 6

where do somatic mutations occur?

Answer 6

in any cell except germ cells and not inheritable

Question 7

where do germ line mutations occur?

Answer 7

in gametes

Question 8

what are autosomal mutations?

Answer 8

occur within genes located on autosomes e.g. not x or y

Question 9

how does a loss of function occur from a mutation?

Answer 9

target gene may be inhibited or not binding where it is supposed to be so less protein production

Question 10

how does a gain of function occur from a mutation?

Answer 10

gene expression when not usually expressed, interact with other proteins so more produced

Question 11

how might imperfect replication cause mutations?

Answer 11

DNA polymerase makes an error, process not accurate enough

Question 12

what are the types of replication damage?

Answer 12

replication slippage and tautomeric shifts

Question 13

what is replication slippage?

Answer 13

loop formed in the template strand so polymerase misses it out and insertions and deletions occurs

Question 14

where is slippage most common?

Answer 14

in common repeat sequences called hot spots

Question 15

how can hot spots cause genetic diseases?

Answer 15

contribute to hereditary diseases such as huntingtons

Question 16

what is a tautomeric shift?

Answer 16

allows non-complementary base pairing and changes the bonding structure

Question 17

what is a tautomer?

Answer 17

an alternate chemical form of purines and pyrimidines

Question 18

what may be caused by a tautomeric shift?

Answer 18

a permanent base pair change and mutations

Question 19

what happens if the damage is not replication related?

Answer 19

becomes a priority of the cell and translation and duplication of DNA prevented

Question 20

what are the types of DNA base damage?

Answer 20

depurination and deamination caused by spontaneous mutations

Question 21

what does DNA base damage lead to?

Answer 21

new base pairing and mutations

Question 22

what is depurination?

Answer 22

loss of a purine forming an apurinic site

Question 23

what is deamination?

Answer 23

removal of an amino group

Question 24

what does deamination cause?

Answer 24

change in base pairing

Question 25

what is oxidative damage?

Answer 25

damage caused by exposure to high energy radiation and cellular products

Question 26

what by products may cause the damage to DNA?

Answer 26

superoxidases, hydroxyl radicals and hydrogen peroxide

Question 27

what are transposable elements?

Answer 27

DNA elements that move within or between genomes

Question 28

what methods do transposable elements use to move?

Answer 28

cut and paste and copy and paste

Question 29

what types of damage do repair systems interact?

Answer 29

spontaneous and inuduced damage

Question 30

what are the pros of DNA repair?

Answer 30

maintains integrity of the genome and counteracts cancer causing damage

Question 31

what are the types of replication associated repair?

Answer 31

proofreading and mismatch repair

Question 32

what is proofreading?

Answer 32

polymerase uses 3' to 5' exonuclease to remove the incorrect base

Question 33

what is mismatch repair?

Answer 33

mis-paired nucleotide and its neighbours are removed and replaced by correct nueleotide, sealed by ligase

Question 34

what are the other types of DNA repair?

Answer 34

direct reversal, excision repair and double stranded break repair

Question 35

what is direct reversal?

Answer 35

damage directly undone by cellular enzymes via photoreactivation to seperate two pyrimidines

Question 36

what is base excision repair?

Answer 36

DNA glycosylase detects the altered base and removes it

Question 37

what is nucleotide excision repair?

Answer 37

repairs bulky lesions that alter or distort the double helix by cutting out thymine dimer

Question 38

how does both base and nucleotide repair work?

Answer 38

light dependant repair mechanism where exonuclease cuts out the error, polymerase seals the gap and ligase joins the nick