DNA Repair mechanisms

Question 1

what is mutation

Answer 1

an alteration in DNA sequence

Question 2

classification of mutation

Answer 2

1. Point mutation or base substitution
   Missense mutation
   Nonsense mutation
   Silent mutation

Question 3

which mutation results in new triplet code for different amino acid

Answer 3

missense

Question 4

which mutation results in triplet code for stop codon (translation terminated prematurely)

Answer 4

nonsense

Question 5

which mutation results in triplet codes for the same amino acid

Answer 5

silent

Question 6

what are the type of base substitutions mutation

Answer 6

transitions and tranversion

Question 7

when pyrimidine replaces pyrimidine or purine replaces purine

Answer 7

transitions

Question 8

when purine and pyrimidne are interchanged

Answer 8

transversion

Question 9

what is the name of mutation that results from insertion or deletion of base pair, loss or addition, frame reading translation is altered

Answer 9

Frameshift mutation

Question 10

somatic mutations occur in which tyoe of cell, are they heritable

Answer 10

occur in any cell except germ cells, are not heritable

Question 11

Germ-line mutations occur in —–, are —-

Answer 11

gametes, are inherited

Question 12

autosomal mutation occur within genes on –

Answer 12

autosomes

Question 13

which mutation arises from normal biological process that alter nitrogenous bases

Answer 13

spontaneous mutation

Question 14

purine and pyrimidines exist in which form?

Answer 14

tautomeric forms, increasing their chances of mispairing

Question 15

loops on the newly synthesized strand results in

Answer 15

adding of one nucleotides

Question 16

loops on temnplate strand results in

Answer 16

omission of one nucleotide

Question 17

is there need for repair of mistake in DNA polymerase action

Answer 17

no rarely

Question 18

what happens when a 3’ to 5’ exonuclease activity is attached to DNA polymerase

Answer 18

it chews back to create a base-paired 3’ OH end on the primer strand

Question 19

Types of DNA damage

Answer 19

1. Deamination
2. Depurination
3. Alkylation

Question 20

what is the damage called when C»U or A» hypoxanthine

Answer 20

deamination

Question 21

what is the damage from A or G lost

Answer 21

depurination

Question 22

guanine oxidizes to 8-oxo-guanine is called

Answer 22

Oxidative damage which causes singel and double strand breaks

Question 23

intercalating agents cause

Answer 23

indels

Question 24

which damage cause cancer mutation and thymine dimers

Answer 24

UV lights

Question 25

what are DNA repair mechanisms

Answer 25

1. BASE excision repair (BER)
2. Nucleotide Excision Repair (NER)

Question 26

Which repair is primary responsible for removing small, non-helix distorting base lesion from the genome

Answer 26

BASE excision repair (BER)

Question 27

which enzyme recognizes and removes damaged base, leaving apyrimidin or apuirnic site

Answer 27

DNA Glycosylase

Question 28

which enzyme removes apyrimidinic or apurinic nucleotide leaving a gap in sugar-phosphaet backbone

Answer 28

AP Endonuclease

Question 29

which repair mechanism is responsible for bulky, helix-distorting lesions, thymine dimers

Answer 29

Nucleotide Excision Repair (NER)

Question 30

what is an accurate mechanism that relies on homology with a sister chromatid to direct DNA synthesis

Answer 30

HR

Question 31

What is an error prone mechanism in which ends are processed to make them compatible and then ligated together by recombination

Answer 31

NHEJ (NON HOMOLOGOUS END JOINING

Question 32

BRCA 1

Answer 32

actiavtes checkpoint

Question 33

BRCA2

Answer 33

stimulates recombination

Question 34

wjere is NHEJ most important

Answer 34

G1 when no homologous template for recombination is available