Deck 14: Dna Replication, Damage and Repair

Question 1

What type of bond is made between nucleotides?

A) ester
B) phosphate ester
C) phosphodiester
D) glycosidic
E) none of the above

Answer 1

phosphodiester

Question 2

In the human genome, there are approximate 3.3

A) thousand genes
B) million genes
C) million base pairs
D) billion base pairs
E) none of the above is correct

Answer 2

billion base pairs

Question 3

The 5' end of a polynucleotide contains _____ while the 3' end contains _____.

A) a hydroxyl group; a phosphate group
B) a phosphate group; a hydroxyl group
C) a phosphate group; a phosphate group
D) a hydroxyl group; a hydroxyl group
E) none of the above

Answer 3

a phosphate group; a hydroxyl group

Question 4

An E. coli has _____ replication fork(s) on its single chromosome; humans have _____ replication fork(s) on each chromosome.

A) 1; 1
B) 1; 2
C) 2; 2
D) 2; many
E) many; many

Question 5

Which strand of DNA is replicated exclusively in a discontinuous fashion?

A) forward strand
B) reverse strand
C) leading strand
D) lagging strand
E) the strand that is read in a 5'to 3' direction

Question 6

What effect does a topoisomerase have upon DNA?

A) denatures DNA
B) converts double stranded DNA to single stranded DNA
C) changes the supercoiling of DNA
D) changes B-form DNA to A-form
E) none of the above

Question 7

What is the purpose of DNA helicase?

A) removal of supercoiling to allow for replication
B) synthesis of RNA primer in front of DNA polymerase
C) separation of double stranded DNA into single stranded DNA in front of DNA polymerase
D) conversion of single stranded DNA to double stranded DNA behind DNA polymerase
E) none of the above

Question 8

Besides the obvious role of keeping DNA in a single strand state, what do single-strand binding proteins do?

A) prevent supercoiling
B) protect single strand DNA backbone from nucleases
C) aid in the formation of hairpin structures
D) aid DNA polymerase with DNA binding
E) all of the above

Question 9

Which is true of Klenow fragments?

A) They are the result of removal of the proofreading domain of a prokaryotic DNA polymerase
B) They result from treatment of ligase with a protease
C) Protease treatment of DNA polymerase III can give rise to Klenow fragments
D) They are another name for Okazaki fragments
E) An important part of the replisome, they block nucleophilic attack on the phosphodiester backbone.

Question 10

Which of the following is correctly paired with its function?

A) helicase: creates single strand DNA
B) primase: production of an RNA primer for DNA polymerase
C) RNase H: removal of RNA primer
D) DNA ligase: joins the discontinuous segments on the lagging strand
E) all of the above

Question 11

The RNA segment to which DNA residues are added during replication is the ______.

Question 12

DNA separated at the replication fork is stabilized by ______.

Question 13

E. coli primer synthesis is catalyzed by ______.

Question 14

The Ter-Tus system is important to

A) formation of the prokaryotic replisome
B) termination of prokaryotic replication
C) termination of eurkaryotic replication
D) separation of DNA strands during replication
E) stabilization of separated DNA strands during replication

Question 15

Which is NOT true of enzyme processivity?

A) One definition is the number of reactions the enzyme can catalyze before dissociation from substrate dissociation
B) A highly processive DNA polymerase would catalyze incorporation of about 10,000 nucleotides
C) Processivity is only used to characterize DNA polymerases
D) Processivity of DNA polymerases can vary with replicon proteins and enzymes.
E) all of the above are true of enzyme processivity

Question 16

What divalent metal ions are typically found in the active site of DNA polymerase?

A) two Zn²⁺
B) one Zn²⁺ and one Mg²⁺
C) two Mg²⁺
D) one Mg²⁺ and one Ca²⁺
E) two Ca²⁺

Question 17

_________ topoisomerases make double-strand breaks in DNA in a controlled fashion.

Question 18

Use the following diagram to complete the sentences below
"_____ is the enzyme which catalyzes phosphodiester bond formation on both strands. Processivity of DNA pol is increased when associated with ____. DNA untwisting is accomplished by ______."

A) A, C, B
B) A, B, C
C) B, C, A
D) A, D, B
E) A, E, B

Question 19

In the nucleus, DNA is wrapped around _____ to form _____.

A) ribosomes; heterochromatin
B) histones; nucleosomes
C) polyribose; euchromatin
D) polyarginine; 30-nm fibers
E) none of the above

Question 20

Without telomeres, what would happen to the ends of eukaryotic chromosomes during replication?

A) they would be replicated just like the rest of the chromosome
B) they would be mutated
C) they would be lengthened
D) they would be shortened
E) none of the above

Question 21

Synthesis of telomeres requires the enzyme _____, which is a type of _____.

A) telomerase; helicase
B) telomerase; reverse transcriptase
C) ribonuclease; RNA-specific nuclease
D) ribotelomerase; ligase
E) none of the above

Question 22

Which of the following is found in high concentration in all telomeres?

A) A
B) C
C) G
D) T
E) pyrimidines

Question 23

What does a reverse transcriptase do?

A) replicates DNA in a 3' to 5'fashion
B) replicates RNA in a 5' to 3'fashion
C) replicates RNA in a 3' to 5'fashion
D) converts a DNA genome into an RNA genome
E) converts an RNA genome into a DNA genome

Question 24

Which is NOT true of replication licensing

A) It ensures that DNA is replicated only once during a single cell cycle
B) It is "canceled" during the S phase of the cell cycle
C) It "primes" the origins of replication to bind the replisome
D) It is important in prokaryotes
E) It is regulated by the cyclin signaling proteins

Question 25

DNA replication in both E. coli and human require

A) gyrase to assist with clamp loading
B) ligase to ligate Okazaki fragments
C) flap endonuclease-1 or RNase H to remove primers
D) DNA pol III
E) none of the above

Question 26

DNA replication in eukaryotes differs from that in prokaryotes in

A) proteins needed to initiate replication
B) licensing of sites of origins of replication
C) how histones are removed for access to template strands
D) the proteins involved in the replication process
E) all of the above

Question 27

What is NOT true of PCNA (proliferating cell nuclear antigen)?

A) It assists the replisome by holding the polymerase to the template strand
B) It increases the processivity of polymerase I
C) It associates with Replication factor C (RFC)
D) none of the above is not true

Question 28

Direct reversal of pyrimidine dimers in prokaryotic cells is catalyzed by a DNA _____.

Question 29

Which is NOT true of intercalators?

A) They slip between bases of DNA
B) They are generally planar molecules, due to their fused-ring structures
C) They are hydrophobic
D) They interact with DNA through weak, non-covalent interactions
E) They can be resolved by nucleotide excision repair

Question 30

A common cause of DNA alkylations is

A) UV light
B) nitrosamines
C) reactive radicals
D) topoisomerase inhibitors
E) viruses

Question 31

In prokaryotes, Mut proteins

A) recognize and bind to mismatches
B) cleaves the newly synthesized strand at the site of a mismatch
C) recognizes and binds to alkylated bases
D) both (A) and (B) are correct
E) all of the above

Question 32

Which type of DNA repair is used to remove and replace a single modified base that cannot be converted back to the normal base by a direct repair process?

A) base excision repair
B) nucleotide excision repair
C) mismatch repair
D) DNA photolyase
E) none of the above

Question 33

Which of the following is a potential modification to DNA that can result in a mutation or interfere with replication or transcription?

A) deamination of cytosine to uracil
B) oxidation of guanine to 8-oxoguanine
C) formation of thymine dimers by reaction with UV light
D) reaction with hydroxyl radicals causing DNA strand breaks
E) all of the above

Question 34

What is the process used for genes shuffling in meiosis that is also used to repair double-strand breaks?

A) homologous end-joining
B) nonhomologous end-joining
C) recombination
D) non-mutagenic strand coupling
E) telomerase-assisted ligation

Question 35

Genes can be moved by _______.

Question 36

In prokaryotes, the RecBCD recombination pathway requires

A) an 8-base Chi sequence
B) binding of RecA to DNA as a first step
C) RecBCD to bind to single-strand DNA after DNA nicking
D) a primer to be laid down by primase
E) all of the above

Question 37

What term is used to describe short segments of DNA that are copied many times and inserted randomly in chromosomes?

A) moderately repetitive sequences
B) highly repetitive sequences
C) transposable elements
D) spliced sequences
E) none of the above

Question 38

Class II transposons

A) are also termed retrotransposons
B) are single stranded DNA segments
C) are "cut and pasted"
D) rely on transposases, enzymes that convert cDNA to double stranded DNA prior to
Insertion
E) none of the above is correct