Question 1

Use the following list of choices for the following questions:
I. helicase
II. DNA polymerase III
III. ligase
IV. DNA polymerase I
V. primase
-Which of the enzymes separates the DNA strands during replication?

Accepted Answer

A)   I
B)   II
C)   III
D)   IV
E)   VF) C) and D)
G) C) and E)

Question 2

Which of the following represents the order of increasingly higher levels of organization of chromatin?

Accepted Answer

A)   nucleosome, 30-nm chromatin fiber, looped domain
B)   looped domain, 30-nm chromatin fiber, nucleosome
C)   looped domain, nucleosome, 30-nm chromatin fiber
D)   nucleosome, looped domain, 30-nm chromatin fiber
E)   30-nm chromatin fiber, nucleosome, looped domainF) C) and D)
G) A) and D)

Question 3

E. coli cells grown on ¹⁵N medium are transferred to ¹⁴N medium and allowed to grow for two more generations (two rounds of DNA replication) . DNA extracted from these cells is centrifuged. What density distribution of DNA would you expect in this experiment?

Accepted Answer

A)   one high-density and one low-density band
B)   one intermediate-density band
C)   one high-density and one intermediate-density band
D)   one low-density and one intermediate-density band
E)   one low-density bandF) C) and E)
G) A) and C)

Question 4

Why do histones bind tightly to DNA?

Accepted Answer

A)   Histones are positively charged, and DNA is negatively charged.
B)   Histones are negatively charged, and DNA is positively charged.
C)   Both histones and DNA are strongly hydrophobic.
D)   Histones are covalently linked to the DNA.
E)   Histones are highly hydrophobic, and DNA is hydrophilic.F) A) and D)
G) A) and E)

Question 5

In a linear eukaryotic chromatin sample, which of the following strands is looped into domains by scaffolding?

Accepted Answer

A)   DNA without attached histones
B)   DNA with H1 only
C)   the 10-nm chromatin fiber
D)   the 30-nm chromatin fiber
E)   the metaphase chromosomeF) A) and B)
G) B) and E)

Question 6

Which of the following statements is true of histones?

Accepted Answer

A)   Each nucleosome consists of two molecules of histone H1.
B)   Histone H1 is not present in the nucleosome bead; instead, it draws the nucleosomes together.
C)   The carboxyl end of each histone extends outward from the nucleosome and is called a "histone tail."
D)   Histones are found in mammals, but not in other animals or in plants or fungi.
E)   The mass of histone in chromatin is approximately nine times the mass of DNA.F) B) and C)
G) A) and E)

Question 7

The enzyme telomerase solves the problem of replication at the ends of linear chromosomes by which method?

Accepted Answer

A)   adding a single 5' cap structure that resists degradation by nucleases
B)   causing specific double-strand DNA breaks that result in blunt ends on both strands
C)   causing linear ends of the newly replicated DNA to circularize
D)   adding numerous short DNA sequences such as TTAGGG, which form a hairpin turn
E)   adding numerous GC pairs which resist hydrolysis and maintain chromosome integrityF) All of the above
G) A) and B)

Question 8

For a science fair project, two students decided to repeat the Hershey and Chase experiment, with modifications. They decided to label the nitrogen of the DNA, rather than the phosphate. They reasoned that each nucleotide has only one phosphate and two to five nitrogens. Thus, labeling the nitrogens would provide a stronger signal than labeling the phosphates. Why won't this experiment work?

Accepted Answer

A)   There is no radioactive isotope of nitrogen.
B)   Radioactive nitrogen has a half-life of 100,000 years, and the material would be too dangerous for too long.
C)   Avery et al. have already concluded that this experiment showed inconclusive results.
D)   Although there are more nitrogens in a nucleotide, labeled phosphates actually have 16 extra neutrons; therefore, they are more radioactive.
E)   Amino acids (and thus proteins)  also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.F) A) and B)
G) C) and D)

Question 9

In his transformation experiments, what did Griffith observe?

Accepted Answer

A)   Mutant mice were resistant to bacterial infections.
B)   Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form.
C)   Mixing a heat-killed nonpathogenic strain of bacteria with a living pathogenic strain makes the pathogenic strain nonpathogenic.
D)   Infecting mice with nonpathogenic strains of bacteria makes them resistant to pathogenic strains.
E)   Mice infected with a pathogenic strain of bacteria can spread the infection to other mice.F) A) and B)
G) A) and C)

Question 10

Studies of nucleosomes have shown that histones (except H1) exist in each nucleosome as two kinds of tetramers: one of 2 H2A molecules and 2 H2B molecules, and the other as 2 H3 and 2 H4 molecules. Which of the following is supported by this data?

Accepted Answer

A)   DNA can wind itself around either of the two kinds of tetramers.
B)   The two types of tetramers associate to form an octamer.
C)   DNA has to associate with individual histones before they form tetramers.
D)   Only H2A can form associations with DNA molecules.
E)   The structure of H3 and H4 molecules is not basic like that of the other histones.F) A) and E)
G) B) and D)

Question 11

Use the following list of choices for the following questions:
I. helicase
II. DNA polymerase III
III. ligase
IV. DNA polymerase I
V. primase
-Which of the enzymes covalently connects segments of DNA?

Accepted Answer

A)   I
B)   II
C)   III
D)   IV
E)   VF) A) and B)
G) B) and D)

Question 12

Grains represent radioactive material within the replicating eye.
-In an experiment, DNA is allowed to replicate in an environment with all necessary enzymes, dATP, dCTP, dGTP, and radioactively labeled dTTP (³H thymidine) for several minutes and then switched to nonradioactive medium. It is then viewed by electron microscopy and autoradiography. The figure above represents the results.
Which of the following is the most likely interpretation?

Accepted Answer

A)   There are two replication forks going in opposite directions.
B)   Thymidine is only being added where the DNA strands are furthest apart.
C)   Thymidine is only added at the very beginning of replication.
D)   Replication proceeds in one direction only.E) A) and D)
F) A) and C)

Question 13

In E. coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin. Which of the following would you expect as a result of this mutation?

Accepted Answer

A)   No proofreading will occur.
B)   No replication fork will be formed.
C)   The DNA will supercoil.
D)   Replication will occur via RNA polymerase alone.
E)   Replication will require a DNA template from another source.F) All of the above
G) B) and E)

Question 14

Which of the following investigators was/were responsible for the following discovery?
In DNA from any species, the amount of adenine equals the amount of thymine, and the amount of guanine equals the amount of cytosine.

Accepted Answer

A)   Frederick Griffith
B)   Alfred Hershey and Martha Chase
C)   Oswald Avery, Maclyn McCarty, and Colin MacLeod
D)   Erwin Chargaff
E)   Matthew Meselson and Franklin StahlF) C) and D)
G) A) and B)

Question 15

Which of the following would you expect of a eukaryote lacking telomerase?

Accepted Answer

A)   a high probability of somatic cells becoming cancerous
B)   production of Okazaki fragments
C)   inability to repair thymine dimers
D)   a reduction in chromosome length in gametes
E)   high sensitivity to sunlightF) None of the above
G) C) and D)

Question 16

What is the function of topoisomerase?

Accepted Answer

A)   relieving strain in the DNA ahead of the replication fork
B)   elongating new DNA at a replication fork by adding nucleotides to the existing chain
C)   adding methyl groups to bases of DNA
D)   unwinding of the double helix
E)   stabilizing single-stranded DNA at the replication forkF) B) and D)
G) A) and B)

Question 17

-A space probe returns with a culture of a microorganism found on a distant planet. Analysis shows that it is a carbon-based life-form that has DNA. You grow the cells in ¹⁵N medium for several generations and then transfer them to ¹⁴N medium. Which pattern in the figure above would you expect if the DNA was replicated in a conservative manner?

Accepted Answer

A)   A
B)   B
C)   C
D)   D
E)   EF) C) and D)
G) B) and E)

Question 18

Which of the following help(s) to hold the DNA strands apart while they are being replicated?

Accepted Answer

A)   primase
B)   ligase
C)   DNA polymerase
D)   single-strand binding proteins
E)   exonucleaseF) C) and D)
G) A) and E)

Question 19

Use the following list of choices for the following questions:
I. helicase
II. DNA polymerase III
III. ligase
IV. DNA polymerase I
V. primase
-Which of the enzymes removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments?

Accepted Answer

A)   I
B)   II
C)   III
D)   IV
E)   VF) C) and D)
G) A) and B)

Question 20

-In the late 1950s, Meselson and Stahl grew bacteria in a medium containing "heavy" nitrogen (¹⁵N) and then transferred them to a medium containing ¹⁴N. Which of the results in the figure above would be expected after one round of DNA replication in the presence of ¹⁴N?

Accepted Answer

A)   A
B)   B
C)   C
D)   D
E)   EF) A) and E)
G) A) and D)

Exam 16: The Molecular Basis of Inheritance

E. coli cells grown on ¹⁵N medium are transferred to ¹⁴N medium and allowed to grow for two more generations (two rounds of DNA replication) . DNA extracted from these cells is centrifuged. What density distribution of DNA would you expect in this experiment?

Correct Answer
verified

Which of the following help(s) to hold the DNA strands apart while they are being replicated?

Correct Answer
verified

Why do histones bind tightly to DNA?

Correct Answer
verified

Which of the following represents the order of increasingly higher levels of organization of chromatin?

Correct Answer
verified

Use the following list of choices for the following questions: I. helicase II. DNA polymerase III III. ligase IV. DNA polymerase I V. primase -Which of the enzymes covalently connects segments of DNA?

Correct Answer
verified

Which of the following would you expect of a eukaryote lacking telomerase?

Correct Answer
verified

Which of the following investigators was/were responsible for the following discovery? In DNA from any species, the amount of adenine equals the amount of thymine, and the amount of guanine equals the amount of cytosine.

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified

What is the function of topoisomerase?

Correct Answer
verified

-In the late 1950s, Meselson and Stahl grew bacteria in a medium containing "heavy" nitrogen (¹⁵N) and then transferred them to a medium containing ¹⁴N. Which of the results in the figure above would be expected after one round of DNA replication in the presence of ¹⁴N?

Correct Answer
verified

Which of the following statements is true of histones?

Correct Answer
verified

Use the following list of choices for the following questions: I. helicase II. DNA polymerase III III. ligase IV. DNA polymerase I V. primase -Which of the enzymes separates the DNA strands during replication?

Correct Answer
verified

Studies of nucleosomes have shown that histones (except H1) exist in each nucleosome as two kinds of tetramers: one of 2 H2A molecules and 2 H2B molecules, and the other as 2 H3 and 2 H4 molecules. Which of the following is supported by this data?

Correct Answer
verified

The enzyme telomerase solves the problem of replication at the ends of linear chromosomes by which method?

Correct Answer
verified

Use the following list of choices for the following questions: I. helicase II. DNA polymerase III III. ligase IV. DNA polymerase I V. primase -Which of the enzymes removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments?

Correct Answer
verified

Correct Answer
verified

In his transformation experiments, what did Griffith observe?

Correct Answer
verified

In a linear eukaryotic chromatin sample, which of the following strands is looped into domains by scaffolding?

Correct Answer
verified

In E. coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin. Which of the following would you expect as a result of this mutation?

Correct Answer
verified

Exam 16: The Molecular Basis of Inheritance

E. coli cells grown on ¹⁵N medium are transferred to ¹⁴N medium and allowed to grow for two more generations (two rounds of DNA replication) . DNA extracted from these cells is centrifuged. What density distribution of DNA would you expect in this experiment?

Correct AnswerverifiedShow Answer

Which of the following help(s) to hold the DNA strands apart while they are being replicated?

Correct AnswerverifiedShow Answer

Why do histones bind tightly to DNA?

Correct AnswerverifiedShow Answer

Which of the following represents the order of increasingly higher levels of organization of chromatin?

Correct AnswerverifiedShow Answer

Use the following list of choices for the following questions: I. helicase II. DNA polymerase III III. ligase IV. DNA polymerase I V. primase -Which of the enzymes covalently connects segments of DNA?

Correct AnswerverifiedShow Answer

Which of the following would you expect of a eukaryote lacking telomerase?

Correct AnswerverifiedShow Answer

Which of the following investigators was/were responsible for the following discovery? In DNA from any species, the amount of adenine equals the amount of thymine, and the amount of guanine equals the amount of cytosine.

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

What is the function of topoisomerase?

Correct AnswerverifiedShow Answer

-In the late 1950s, Meselson and Stahl grew bacteria in a medium containing "heavy" nitrogen (¹⁵N) and then transferred them to a medium containing ¹⁴N. Which of the results in the figure above would be expected after one round of DNA replication in the presence of ¹⁴N?

Correct AnswerverifiedShow Answer

Which of the following statements is true of histones?

Correct AnswerverifiedShow Answer

Use the following list of choices for the following questions: I. helicase II. DNA polymerase III III. ligase IV. DNA polymerase I V. primase -Which of the enzymes separates the DNA strands during replication?

Correct AnswerverifiedShow Answer

Studies of nucleosomes have shown that histones (except H1) exist in each nucleosome as two kinds of tetramers: one of 2 H2A molecules and 2 H2B molecules, and the other as 2 H3 and 2 H4 molecules. Which of the following is supported by this data?

Correct AnswerverifiedShow Answer

The enzyme telomerase solves the problem of replication at the ends of linear chromosomes by which method?

Correct AnswerverifiedShow Answer

Use the following list of choices for the following questions: I. helicase II. DNA polymerase III III. ligase IV. DNA polymerase I V. primase -Which of the enzymes removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments?

Correct AnswerverifiedShow Answer

Correct AnswerverifiedShow Answer

In his transformation experiments, what did Griffith observe?

Correct AnswerverifiedShow Answer

In a linear eukaryotic chromatin sample, which of the following strands is looped into domains by scaffolding?

Correct AnswerverifiedShow Answer

In E. coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin. Which of the following would you expect as a result of this mutation?

Correct AnswerverifiedShow Answer

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