Chapter 6 Part 2

Question 1

Why do we need DNA repair mechanisms?

Answer 1

Fidelity of DNA

Question 2

What is spontaneous damage?

Answer 2

It is naturally occurring mutations (depurination and deamination)

Question 3

What is induced damage?

Answer 3

exposure to physical or chemical agent that cause mutation

Question 4

What is Depurination?

Answer 4

Loss of purine base (adenine and guanine)

Question 5

What is the result of depurination?

Answer 5

it may stall replication

Question 6

What leads to mutations?

Answer 6

DNA Damage

Question 7

What is deamination?

Answer 7

removal of the amino group from the base (the amino group is replaced by keto group)

Question 8

What bases does deamination affect?

Answer 8

adenine, guanine, and cytosine

Question 9

What does ultraviolet radiation cause?

Answer 9

pyrimidine dimers (induced mutations)

Question 10

what is the result of the pyrimidine dimers?

Answer 10

DNA Polymerase stalls

Question 11

What diseases causes the inability to fix UV Damage?

Answer 11

Xeroderma Pigmentosum

Question 12

What is the cause of Xeroderma Pigmentosum?

Answer 12

DNA Repair enzyme is mutated

Question 13

What are people who have Xeroderma Pigmentosum called?

Answer 13

children of the night

Question 14

What type of damage does mismatch repair take care of?

Answer 14

Repairs single strand damage

Question 15

How are double strand DNA breaks repaired?

Answer 15

Non-homologous end joining and homologus recombination

Question 16

When does mismatch repair occur?

Answer 16

RIght after new DNA is made

Question 17

How does mismatch repair repair DNA?

Answer 17

It removes mis-paired bases missed by DNA Polymerase, it also picks up deletions and insertions that spontaneously happen

Question 18

Which double-strand DNA repair method is quicker?

Answer 18

non-homologous end joining (its emergency cleanup)

Question 19

What protein is responsible for non-homologous end joining?

Answer 19

DNA Ligase joins the two strands and nuclease processes the DNA end

Question 20

What is the result of non-homologous end joining?

Answer 20

loss of nucleotides at repair site

Question 21

When does homologous recombination occur?

Answer 21

if there are two identical copies of DNA