Deck 10: Non-Mendelian Inheritance

Question 1

As helicase unwinds the DNA molecule, what keeps the strands apart?

A) Replication fork
B) Okazaki fragments
C) DNA polymerase
D) Reverse transcriptase
E) Single-strand binding proteins

Answer 1

E

Question 2

Which enzyme activity is associated with DNA polymerase I?

A) 5' to 3' polymerase
B) 3' to 5' exonuclease
C) 5' to 3' exonuclease
D) Both A and B
E) All of the above

Answer 2

E

Question 3

In eukaryotes, chromosomes are duplicated during which stage of the cell cycle?

A) M
B) G1
C) C1
D) S
E) G2

Answer 3

D

Question 4

Where does the initiator protein bind DNA at the start of replication?

A) At a replication fork
B) At an origin of replication
C) At a promoter region
D) At a start codon
E) At any AT-rich region

Question 5

The two most basic steps of DNA replication are

A) the new strand is denatured and a template is synthesized.
B) helicase unwinds template and DNA polymerase binds.
C) primase causes primer to bind template and ligase copies the template.
D) the template is denatured and a new strand is synthesized.
E) leading strand is copied first and lagging strand second.

Question 6

In both prokaryotes and eukaryotes, DNA replication is

A) bidirectional and semiconservative.
B) bidirectional and dispersive.
C) unidirectional and dispersive.
D) dispersive and semiconservative.
E) unidirectional and semiconservative.

Question 7

What allows for the base-pairing error rate to be kept very low during replication?

A) UV light radiation corrects any base mispairs.
B) DNA repair mechanisms can fix the mispaired bases.
C) Mispaired bases cause the cell to die.
D) Bases that are mispaired can excise themselves.
E) There are no errors.

Question 8

During replication, the direction of synthesis of new DNA from the leading and lagging strands is

A) 3' to 5' only.
B) both 5' to 3' and 3' to 5'.
C) from left to right only.
D) 5' to 3' only.
E) different, depending on whether the cell is prokaryotic or eukaryotic.

Question 9

Which enzyme replaces RNA primers with DNA after elongation?

A) RNA primase
B) DNA polymerase I
C) RNA polymerase
D) DNA ligase
E) DNA polymerase III

Question 10

In E. coli, replication begins at which chromosome site?

A) ter
B) oriC
C) The replication fork
D) TBP
E) Any of the above

Question 11

Which kind of enzyme prevents DNA from tangling up by introducing negative supercoils as the replication fork migrates during replication?

A) Helicase
B) DNA polymerase I
C) Topoisomerase
D) DNA polymerase III
E) Ligase

Question 12

Replication of nuclear DNA in eukaryotes requires

A) Pol alpha only.
B) Pol beta only.
C) Pol alpha and delta.
D) Pol epsilon only.
E) Pol alpha, delta, and epsilon.

Question 13

The enzymatic activity of a telomerase is best described as a

A) polymerase.
B) reverse transcriptase.
C) exonuclease.
D) ligase.
E) topoisomerase.

Question 14

What is a replication bubble?

A) A localized site in the nucleus where chromosomes are replicating
B) A DNA sequence that initiates replication
C) A complex of replication enzymes on the DNA template strand
D) A locally denatured segment of DNA where replication originates
E) A tangle of denatured DNA strands near the replication fork

Question 15

Which enzyme elongates the new DNA strand starting at an RNA primer?

A) DNA polymerase III
B) DNA ligase
C) RNA primase
D) RNA polymerase
E) DNA polymerase I

Question 16

Which of the following are necessary for DNA replication in vitro?

A) DNA can't replicate in vitro
B) Okazaki fragments, helicase, DNA polymerase
C) RNA, helicase, DNA polymerase
D) Template DNA, DNA polymerase, four dNTPs, magnesium ions
E) Template DNA, four dNTPs, and magnesium ions

Question 17

After removal of the RNA primers and replacement with DNA nucleotides, the single-stranded nick adjacent to Okazaki fragments is filled in through a reaction that involves which enzyme?

A) DNA ligase
B) SSB protein
C) DNA primase
D) RNA polymerase
E) DNA helicase

Question 18

After a region of DNA has been replicated, ______ removes the RNA primers.

A) DNA helicase
B) DNA polymerase III
C) DNA ligase
D) DNA polymerase I
E) RNA primase

Question 19

How many replication forks are produced when DNA denatures at an origin?

A) 1
B) 2
C) 0
D) 3
E) The number varies

Question 20

What did Meselson and Stahl's experiment demonstrate?

A) DNA replication is sometimes conservative and sometimes semiconservative.
B) DNA replication is semiconservative.
C) DNA replication is conservative.
D) DNA replication is dispersive.
E) DNA replication is discontinuous.

Question 21

The diploid set of chromosomes in Drosophila embryos replicates six times faster than the single E. coli chromosome, even though there is about 100 times more DNA in Drosophila than in E. coli and the rate of movement of the replication fork in Drosophila is much slower. How is this so?

Question 22

How did Meselson and Stahl rule out the conservative model of DNA replication using equilibrium density gradient centrifugation?

Question 23

How do the DNA polymerase repair mechanisms work?

Question 24

Why is an AT-rich sequence characteristic of DNA replicators in all organisms?

Question 25

DNA polymerase III is very inaccurate at matching bases during replication; errors are made in 1/100 base pairs.

Question 26

In eukaryotic cells, RNA and proteins are actively synthesized during the S phase of the cell cycle.

Question 27

Why is DNA replication called semiconservative?

Question 28

Okazaki fragments are made from the lagging strand of the DNA double helix.

Question 29

Describe Arthur Kornberg's method, which first successfully achieved DNA synthesis in vitro. What were all the components needed for?

Question 30

DNA primase is an enzyme that catalyzes the reaction necessary to synthesize a molecule of DNA.

Question 31

What happens to temperature-sensitive E. coli polAex1 mutants when grown at 37° and at 42°? Why?

Question 32

What are the key replication enzymes at the replisome, and how is DNA replication on both leading and lagging strands made efficient through the conformation of the DNA at the replisome?

Question 33

A new nucleotide is added to a growing strand of DNA at the 3' end.

Question 34

What are some key differences in replication between E. coli DNA and λ phage DNA?

Question 35

What is a method by which you could visualize semiconservative DNA replication in eukaryotes?

Question 36

What are the differences in replication between leading and lagging strands in terms of continuity and directionality in relation to the replication fork?

Question 37

In eukaryotes, DNA replication begins at a single origin of replication on each chromosome.

Question 38

At the growing end of a DNA chain, DNA polymerase catalyzes the formation of a disulfide bond between the 3'-OH group of the deoxyribose on the last nucleotide and the 5'-phosphate of the dNTP precursor.

Question 39

Only the leading strand of a DNA molecule serves as a template during replication.

Question 40

Topoisomerase and SSB proteins are important components of the replication process in prokaryotes, but they are not found in eukaryotes.

Question 41

What evidence is there that telomerase activity is necessary for long-term cell viability?

Question 42

When the RNA primers are removed from the 5' ends of eukaryotic chromosomes after replication, DNA polymerase is unable to fill in the gaps. What prevents the chromosomes from getting shorter and shorter with each round of replication?

Question 43

What is the importance of DNA primase in initiating replication?