L3

Question 1

What is the first line of defense mechanism and what happens if it fails

Answer 1

1st: DNA polymerase 1 3’-5’ exonuclease
2nd: DNA repair system
If they fail: permanent mutation 

Question 2

Which enzyme corrects the error that DNA polymerase 3 creates

Answer 2

3’-5’ exonuclease

Question 3

Depurination causes which type of mutation

Answer 3

Deletion

Question 4

Depurination and deamination are a result of

Answer 4

Hydrolysis

Question 5

Deamination causes which type of mutation

Answer 5

Transition

Question 6

What is the mnemonic that you created for deamination?

Answer 6

See you amar hamad, ganantay xiavier methel tamer

Question 7

Isomers

Answer 7

Tautomeric

Question 8

In tautomeric shift, what errors might occur? And why this creates a problem?

Answer 8

G, T: keto -> enol
A, C: amino —> imine
Because A is misread for G which causes a transition mutation

Question 9

Explain the error in ROS Mediated DNA damage

Answer 9

ROS binds with G —> 8-OHdG
DNA polymerase assumes it’s a T and binds it with A

Question 10

What type of mutation is ROS

Answer 10

Transversion

Question 11

Explain exogenous induced factors

Answer 11

UV attacks T cross-links —> T dimers —> bend DNA —> weaken T-A bonds

Question 12

What type of damage is Exogenous induced 

Answer 12

Uv radiation, structural damage

Question 13

What is the overall principle of the repairing system and Mention the differences. 
BER
NER
MRM

Answer 13

BER:
Uracil DNA glycosalase —> removes uracil

NER:
UvrABC endonuclease —> recognizes damage

MRM
MutS—>MutL—>MutH —> cuts the strand.

Principal pathway
Endonuclease —> cuts the dna strand and flanks the end
Exonuclease —> chew the ntds
DNA pol —> +ntd
Ligase


Question 14

What type of error does each DNA repair system fixes?
BER
NER
MRM

Answer 14

BER: oxidative deamination in which amino group is converted into keto group.

NER: thymine dimers induced by UV

MRM: mis-incorporated bases that can arise during DNA replication, any mismatch

Question 15

What type of DNA polymerase does NER and MRM use

Answer 15

NER: pol1
MRM : pol 3

Question 16

Explain missense mutation

Answer 16

Nucleotide change, codon change, wrong protein

Question 17

Explain nonsense mutation

Answer 17

premature stop codon, truncated, non-functional protein

Question 18

Explain silent mutation

Answer 18

Nucleotide change, codon change, however it’s still codes for the same protein. No effect on the function or the phenotype

Question 19

Is an autosomal recessive disorder

Answer 19

Xeroderma pigmentosum

Question 20

Defect in repairing thymine dimers result in which disorder

Answer 20

Xeroderma pigmentosum

Question 21

Xeroderma pigmentosum is an error in which repair system

Answer 21

NER

Question 22

Patience with this disorder are photosensitive and susceptible to skin cancer

Answer 22

Xeroderma pigmentosum

Question 23

Is a degenerative motor condition

Answer 23

Ataxia-telangiectasia

Question 24

Ataxia-telangiectasia is a result of a defect in which repairing system

Answer 24

BER

Question 25

What gene is mutated in Ataxia-telangiectasia 

Answer 25

ATM

Question 26

Which disorder affects the immune system and the other body parts

Answer 26

Ataxia-telangiectasia

Question 27

Mutation in which genes results in Hereditary Nonpolyposis Colon Cancer 

Answer 27

MRM