Lecture 9

Question 0

When do mutations most commonly occur?

Answer 0

During DNA replication

Question 1

What strand breakage is most commonly induced by radiation?

Answer 1

Double strand breaks

Question 2

What percentage of DNA mutations are repaired by repair pathways?

Answer 2

99%

Question 3

What does strand slippage cause?

Answer 3

Mutations via insertions/deletions of base pairs

Question 4

Where do strand slippage mutations most commonly occur?

Answer 4

Areas of repeated DNA

Question 5

What type of virus requires integration into host chromosomes?

Answer 5

Retrovirus

Question 6

What are transposons?

Answer 6

Inherited DNA sequences that can cut and paste themselves from one location to another in the genome

Question 7

What type of DNA are transposons?

Answer 7

Repetitive

Question 8

How can transposons lead to cancer?

Answer 8

Overproduction of oncogene proteins by insertional activation

Question 9

Alu transposon insertion results in what two cancers?

Answer 9

Neurofibromatosis type 1 and bladder carcinoma

Question 10

Transposon miso airing can cause

Answer 10

Unequal crossing over, deletion/duplication

Question 11

What are the five types of DNA repair?

Answer 11

Direct repair, base excision repair, nucleotide excision repair, mismatch repair, and recombinational repair

Question 12

Which type of DNA repair deals with broad class helix-distorting lesions that disrupt transcription and replication?

Answer 12

Nucleotide excision repair (NER)

Question 13

Which repair pathway deals with small chemical alterations if bases and is particularly important for preventing mutation?

Answer 13

Base excision repair (BER)

Question 14

Which repair pathway corrects replication errors and can repair alkylated bases?

Answer 14

Mismatch repair (MMR)

Question 15

Which repair pathway includes homologous recombination (HR) and non-homologous end joining (NHEJ)?

Answer 15

Double-strand break (DSB) repair

Question 16

What are the four steps of nucleotide excision repair?

Answer 16

Dual incision of unwound DNA on both sides of lesion, excision of damaged DNA, repair by polymerization, ligation

Question 17

What are the two subpathways of NER?

Answer 17

Global genome repair (GGR) and transcription coupled repair (TCR)

Question 18

Where does GGR function?

Answer 18

Entire genome

Question 19

Where does TCR function?

Answer 19

Lesions specifically blocking transcription

Question 20

Which DNA repair pathway is important for fixing UV damage?

Answer 20

Nucleotide excision repair (NER)

Question 21

What are the three genetic disorders causes by mutated NER?

Answer 21

Xeroderma Pigmentosum (XP), Cockayne’s Syndrome (CS), and TrichoThioDystrophy (TTD)

Question 22

What are four types of base damage that base excision repair is responsible for fixing?

Answer 22

Oxidative lesions, alkylation products, bulky DNA adducts, and base hydrolysis

Question 23

What enzyme removes uracil from the DNA?

Answer 23

Uracil-DNA glycosylase (UNG/UDG)

Question 24

How dose base excision repair (BER) work?

Answer 24

Single nucleotide is excised, DNA polymerase β fills gap, DNA ligase III seals gap

Question 25

What protein is responsible for the recognition of abnormal DNA bass?

Answer 25

DNA glycosylase

Question 26

What does DNA glycosylase do once it recognizes and binds DNA at abnormal site?

Answer 26

Hydrolytically cleaves base off sugar backbone, creating an AP site (apurine/apyrimidine)

Question 27

What are three important AP endonucleases?

Answer 27

hAPE, hAP1, REF1

Question 28

Direct reversal DNA repair is responsible for what?

Answer 28

Dealkylating affected bases