Nucleotides, DNA, Replication, and Repair

Question 1

DNA replication occurs during this phase of the cell cycle

Answer 1

S phase

Question 2

Number of H bonds between G and C pairs

Answer 2

3

Question 3

this enzyme is necessary for DNA polymerase III to complete replication of the lagging strand at the end of the chromosome

Answer 3

telomerase

Question 4

this enzyme joins Okazaki fragments together

Answer 4

DNA ligase

Question 5

de novo synthesis

Answer 5

pyrimidine and purine nucleotides are synthesized from amino acids, carbon dioxide, folate derivatives, and PRPP

Question 6

nucleotide salvage

Answer 6

uses free bases (recycling) via a reaction with PRPP to generate nucleotides, there needs to be a balance of breakdown and recycling

Question 7

helicase

Answer 7

unzipping enzyme, breaks through hydrogen bonds that hold DNA bases together

Question 8

DNA polymerase

Answer 8

the building enzyme, has proofreading ability, replicates DNA molecules to build a new strand

Question 9

primase

Answer 9

the initializer, primer, used so polymerase knows where to go to start

Question 10

ligase

Answer 10

the gluer, helps glue DNA fragments together, has to take care of the gaps between Okazaki fragments, sealing them together

Question 11

topoisomerase

Answer 11

keeps DNA from super coiling (overwinding) of DNA ahead of replication fork

Question 12

topoisomerase I

Answer 12

makes a single stranded break, unwinds the DNA, and reseals the ends of the broken strand

Question 13

topoisomerase II

Answer 13

makes a double stranded break, unwinds the DNA, and reseals the ends

Question 14

first step in DNA replication

Answer 14

helicase unwinds parental double helix

Question 15

purines

Answer 15

adenine and guanine

Question 16

pyrimidines

Answer 16

cytosine, thymine, and uracil

Question 17

telomere

Answer 17

a region of repetitive nucleotide sequences at each end of a chromosome

Question 18

telomerase

Answer 18

elongates the template strand in 5’ - 3’ direction

Question 19

the 2 components necessary for both de novo and salvage nucleotide synthesis

Answer 19

PRPP and folate

Question 20

this type of DNA repair typically repairs deamination, deprivation, and oxidative damage

Answer 20

base excision repair

Question 21

inhibition of this enzyme will decrease uric acid levels

Answer 21

xanthine oxidase

Question 22

pyrimidine dimers can occur due to radiation damage and are repaired by this mechanism

Answer 22

nucleotide excision repair

Question 23

gene

Answer 23

a portion of the DNA sequence with instructions for synthesis of a functional product (a protein or a functional RNA molecule)