DNA Replication, Repair, and Mutagenesis

Question 1

origin of replication

Answer 1

initiation sites for DNA replication

Question 2

T-ag (T-antigen)

Answer 2

viral protein needed for eukaryotic “model system” studies, also a helicase

Question 3

helicase

Answer 3

enzyme that disrupts hydrogen bonds of dsDNA

Question 4

RPA

Answer 4

Human single stranded binding protein

Question 5

Bloom’s Syndrome

Answer 5

Disease in which helicase is deficient; high risk of developing malignancies (leukemia)

Question 6

Werner’s Syndrome

Answer 6

Disease in which a helicase is defective, causes premature aging

Question 7

DNA primase

Answer 7

Synthesizes RNA primer to initiate replication

Question 8

pol alpha-primase complex

Answer 8

Synthesizes DNA primer, necessary to initiate transcription

Question 9

Pol epsilon

Answer 9

DNA polymerase that adds nucleotides to the leading strand

Question 10

Pol delta

Answer 10

DNA polymerase that adds nucleotides to the lagging strand

Question 11

PCNA

Answer 11

Proliferating Cell Nuclear Antigen - clamps the polymerases to the DNA

Question 12

RFC

Answer 12

Replication Factor C - loads polyermases onto the DNA

Question 13

Okazaki fragments

Answer 13

lagging strand fragments of DNA

Question 14

DNA ligase

Answer 14

covalently links the Okazaki fragments of the lagging strand

Question 15

Acyclovir

Answer 15

inhibits DNA polymerase encoded by herpes simplex virus but termination replication

Question 16

AZT (Azidothymidine)

Answer 16

inhibits reverse transcriptase encoded by HIV

Question 17

kinases

Answer 17

enzymes that add phosphate groups to other molecules

Question 18

cyclin/cyclin dependent kinases

Answer 18

important in regulating the cell cycle

Question 19

p53 protein

Answer 19

prevents cells from dividing if they have damaged DNA, if mutated, cancer can result

Question 20

mismatch repair

Answer 20

mechanism for removing incorrect bases in DNA

Question 21

Mut S

Answer 21

recognizes DNA mismatch

Question 22

Mut H

Answer 22

catalyzes DNA strand incision for mismatch repair

Question 23

Mut L

Answer 23

Thought to provide a protein-protein interface for mismatch repair

Question 24

Trinucleotide repeats

Answer 24

repeating sequences of three nucleotides that can lead to disease, stabilized by mismatch repair pathways

Question 25

excision repair

Answer 25

removal of a faulty DNA segment by DNA synthesis

Question 26

uvrABC

Answer 26

recognizes and cleaves damaged DNA strand of pyrimidine dimer in excision repair

Question 27

xerderma pigmentosum

Answer 27

disease from biochemical defects of excision repair process

Question 28

Li-Fraumeni Syndrome

Answer 28

individuals with mutant p53, can’t arrest cell cycle if DNA is damaged

Question 29

Hereditary non-polyposis colon cancer (HNPCC)

Answer 29

mutations in mismatch repair genes leads to a predisposition to cancers

Question 30

Fragile X Syndrome, Myotonic Dystrophy, Huntingtons Disease

Answer 30

trinucleotide repeat disorders

Question 31

uracil-DNA glycosidase

Answer 31

removes inappropriate uracil, leaving AP site

Question 32

deamination

Answer 32

cytosine converts to uracil OR adenine converts to hypoxanthine (G)

Question 33

methylation

Answer 33

leads to loss of guanine residue due to labilization of N-glycosidic linkage

Question 34

intercaltors

Answer 34

get between bases of DNA, disturb double helical structure

Question 35

examples of intercaltors

Answer 35

ethidium bromide, proflain, acridine orange