CHAPTER 14—DNA STRUCTURE, REPLICATION, AND ORGANIZATION
MULTIPLE CHOICE
1. The genetic material of all living organisms is
a.
protein.
b.
deoxyribonucleic acid.
c.
ribonucleic acid.
d.
glycoprotein.
e.
polypeptide.
2. Watson and Crick are famous for determining
a.
the presence of nuclein (DNA) in pus cells.
b.
the role of DNA in cells.
c.
what chemical components are in DNA.
d.
the three-dimensional structure of DNA.
e.
the location of DNA in cells.
3. Prior to the 1940s, many biologists thought that ____, being made up of 20 types of ____, was the best
candidate for genetic material.
a.
protein; amino acids
b.
DNA; amino acids
c.
protein; nucleotides
d.
DNA; nucleotides
e.
RNA; nucleotides
4. What happens when living R strain Streptococcus pneumoniae bacteria are mixed with heat-killed S
strain Streptococcus pneumoniae bacteria?
a.
The S strain bacteria come back to life.
b.
The R strain bacteria are killed, and the S strain bacteria remain dead.
c.
The R strain bacteria are transformed into S strain bacteria.
d.
The S strain bacteria are transformed into R strain bacteria.
e.
The R strain bacteria are killed, and the S strain bacteria come back to life.
5. The transforming principle that Griffith described from his work with Streptococcus pneumoniae
bacteria turned out to be ____.
a.
a polysaccharide capsule
b.
a phospholipid
c.
protein
d.
RNA
e.
DNA
6. Avery, McLeod, and McCarty continued Griffith’s work with S. pneumoniae and concluded from their
experiments that DNA was the hereditary material. What would happen to mice after injection of heat-
killed virulent bacteria mixed with live avirulent bacteria after treatment with proteinase if protein was
the hereditary material instead of DNA?
a.
the mice would live
b.
the mice would die
c.
the mice would get sick but recover
d.
the mice would grow tumors
e.
the mice would degrade the protein
7. In their experiments to determine the transforming principle, Avery, MacLeod, and McCarty used
enzymes that break down ____.
a.
protein, DNA, and RNA
b.
protein and RNA
c.
DNA
d.
protein, lipids, and RNA
e.
lipids and DNA
8. In the Hershey and Chase experiment, the pellet was radioactive after bacteria had been infected with
32P-labeled viruses and centrifuged. Why?
a.
Bacteria were centrifuged to form the pellet, and they had incorporated radioactive
proteins into their DNA.
b.
Bacteria were centrifuged to form the pellet, and they had incorporated radioactive DNA.
c.
Viruses were centrifuged to form the pellet, and they had incorporated radioactive proteins
from the bacterial DNA.
d.
Bacteria were centrifuged to form the pellet, and they had incorporated radioactive
proteins into their cell membranes.
e.
Viruses were centrifuged to form the pellet, and they had incorporated radioactive DNA.
9. When Hershey and Chase labeled viruses with radioactive phosphorus, they concluded that the virus
injects DNA and not protein into its host because the
a.
radioactive protein ended up inside the bacterium
b.
radioactive DNA ended up inside the bacterium
c.
both radioactive DNA and protein ended up inside the bacterium
d.
neither radioactive DNA nor protein ended up inside the bacterium
e.
entire virus ended up inside the bacterium
10. The T2 bacteriophages used in the Hershey and Chase experiment are made of what?
a.
DNA
b.
RNA and protein
c.
protein, phospholipid, and DNA
d.
DNA and protein
e.
protein, phospholipid, DNA, and RNA
11. In the Hershey and Chase experiment, 32P was used to label ____ and 35S was used to label ____.
a.
RNA; protein
b.
protein; DNA
c.
phospholipids; protein
d.
protein; phospholipids
e.
DNA; protein
12. Each DNA nucleotide is made up of
a.
a six-carbon sugar, a phosphate group, and one of twenty amino acids.
b.
a five-carbon sugar, a nitrogenous base, and one of twenty amino acids.
c.
a five-carbon sugar, a phosphate group, and one of four nitrogenous bases.
d.
a six-carbon sugar, a nitrogenous base, and one of four amino acids.
e.
a five-carbon sugar, a phosphate group, and one of four amino acids.
13. Adjacent nucleotides on a strand of DNA are connected to each other by a(n) ____.
a.
hydrophobic interaction
b.
phosphodiester bond
c.
hydrogen bond
d.
peptide bond
e.
ionic bond
14. If a stretch of human double stranded DNA contains 47% G + C, then
a.
it contains 47% A + T
b.
there are more pyrimidines than purines
c.
there are more purines than pyrimidines
d.
it contains 53% A + T
e.
there are no genes in this stretch of DNA
15. The DNA of an organism is studied and found to contain 14% guanine. This organism should have
____% thymine and ____% cytosine in its DNA.
a.
86; 14
b.
14; 36
c.
36; 36
d.
14; 86
e.
36; 14
16. The DNA of an organism is studied and found to contain 30% adenine. Based on this you would
predict that the DNA of this organism also contains 30% ____.
a.
thymine
b.
cytosine
c.
each of cytosine and guanine
d.
each of thymine and guanine
e.
guanine
17. In DNA the purines are
a.
thymine and cytosine.
b.
adenine and cytosine.
c.
adenine and guanine.
d.
thymine and adenine.
e.
guanine and thymine.
18. In DNA the pyrimidines are
a.
thymine and cytosine.
b.
adenine and cytosine.
c.
adenine and guanine.
d.
thymine and adenine.
e.
guanine and thymine.
19. Which of the following nitrogenous bases is NOT normally found in DNA?
a.
thymine
b.
cytosine
c.
adenine
d.
uracil
e.
guanine
20. Which of the following nucleotide sequences represents the complementary sequence that would bind
to the DNA strand 5′-GACGTT-3′?
a.
5′−TCATGG−3′
b.
3′−TCATGG−5′
c.
3′−CTGCAA−5′
d.
3′−AGTACC−5′
e.
5′−TTGCAG−3′
21. Wilkins and Franklin studied the structure of DNA using ____.
a.
molecular scale models of nucleotides
b.
X-ray diffraction
c.
computer-assisted graphics
d.
electron microscopy
e.
light microscopy
22. A DNA double helix has two strands that are held to each other by ____.
a.
hydrogen bonds
b.
ionic bonds
c.
hydrophobic interactions
d.
phosphodiester bonds
e.
covalent bonds
23. The width of a DNA double helix
a.
is constant.
b.
is narrower where adenine is present than where cytosine is present.
c.
is wider where purines are present than where pyrimidines are present.
d.
varies randomly.
e.
is wider where pyrimidines are present than where purines are present.
24. The two strands of a DNA double helix are said to be antiparallel. This means that
a.
the 5′ end of one strand is directly paired with the 5′ end of the other strand.
b.
since the double helix twists, it is not perfectly parallel.
c.
one strand has a negative charge and the other strand has a positive charge.
d.
the 5′ end of one strand is directly paired with the 3′ end of the other strand.
e.
both strands have a negative charge.
25. DNA replication is said to be semiconservative because
a.
the number of nucleotides within genes remains constant.
b.
half of the DNA in a cell comes from one parent and the other half from the other parent.
c.
the same process of DNA replication is used by all organisms.
d.
the total amount of DNA within an individual remains the same.
e.
each new DNA molecule is composed of one old strand and one new strand.
26. In the Meselson-Stahl experiment, bacterial DNA was labeled completely with heavy nitrogen (N-15)
and then grown in the presence of light nitrogen (N-14). When only mixed DNA was observed after
ONE generation of growth in N-14, what was the conclusion?
a.
DNA replication is semiconservative
b.
DNA replication is conservative
c.
DNA replication is dispersive
d.
DNA replication is either semiconservative or dispersive
e.
DNA replication is either semiconservative or conservative
27. The figure above depicts the result of an experiment to determine how DNA replication occurs. Based
on these results, it appears that after replication each DNA molecule is made of
a.
either entirely old DNA strands or entirely new DNA strands.
b.
one old DNA strand and one new DNA strand.
c.
entirely new DNA.
d.
some DNA helix regions that are old DNA, alternating with some DNA regions that are
new DNA.
e.
two strands that are each a mix of old and new DNA.
Use the figure above for the following question(s).
28. The structure labeled “A” in this figure of a replication fork represents ____.
a.
single-stranded binding protein
b.
primase
c.
DNA ligase
d.
helicase
e.
DNA polymerase
29. The structure labeled “B” in this figure of a replication fork represents ____.
a.
single-stranded binding protein
b.
primase
c.
DNA ligase
d.
helicase
e.
DNA polymerase
30. The structure labeled “C” in this figure of a replication fork represents ____.
a.
single-stranded binding protein
b.
primase
c.
DNA ligase
d.
helicase
e.
DNA polymerase
31. The structure labeled “D” in this figure of a replication fork represents ____.
a.
single-stranded binding protein
b.
primase
c.
DNA ligase
d.
helicase
e.
DNA polymerase
32. The structure labeled “E” in this figure of a replication fork represents ____.
a.
single-stranded binding protein
b.
primase
c.
DNA ligase
d.
helicase
e.
DNA polymerase
33. Which of the following adds individual nucleotides to the 3′ end of an existing strand to build a new
DNA strand during DNA replication?
a.
topoisomerase
b.
primase
c.
DNA polymerase
d.
helicase
e.
DNA ligase
34. Which of the following acts to remove overtwisting and strain ahead of the replication fork during
DNA replication?
a.
topoisomerase
b.
primase
c.
DNA polymerase
d.
helicase
e.
DNA ligase
35. The active site of DNA polymerase is similar
a.
in archaea and bacteria only
b.
in archaea, bacteria, and eukaryotes
c.
in archaea and eukaryotes only
d.
in none of these groups
e.
in bacteria and eukaryotes only
36. Which of the following closes “nicks” between DNA fragments, forming a covalent bond that ties or
joins the fragments together?
a.
topoisomerase
b.
primase
c.
DNA polymerase
d.
helicase
e.
DNA ligase
37. Which of the following catalyzes the unwinding of the DNA double helix during DNA replication?
a.
topoisomerase
b.
primase
c.
DNA polymerase
d.
helicase
e.
DNA ligase
38. Which of the following assembles a short RNA chain as the first nucleotides in a new DNA strand?
a.
topoisomerase
b.
primase
c.
DNA polymerase
d.
helicase
e.
DNA ligase
39. During DNA replication, DNA ligase is most active on the lagging strand. Why?
a.
The lagging strands contain more short DNA segments than the leading strand, and these
short segments are joined together by DNA ligase.
b.
The lagging strand is synthesized more slowly, and DNA ligase speeds up the DNA
polymerase.
c.
The lagging strand synthesizes DNA in the 3′ → 5′ direction.
d.
The lagging strand requires DNA ligase to couple the RNA primer to the Okazaki
fragments.
e.
The lagging strand has no RNA primase activity; it is replaced by DNA ligase.
40. Adding nucleotides onto a growing DNA strand during DNA replication in cells occurs in
a.
the 5′ → 3′ direction for the leading strand and the 3′ → 5′ direction on the lagging strand.
b.
either the 5′ → 3′ direction or the 3′ → 5′ direction on both strands, depending on where
replication begins.
c.
the 5′ → 3′ direction only.
d.
the 3′ → 5′ direction for the leading strand and the 5′ → 3′ direction on the lagging strand.
e.
the 3′ → 5′ direction only.
41. Reiji Okazaki discovered that what are now called “Okazaki fragments” produced during DNA
replication. These are
a.
short lengths of new DNA on the leading strand.
b.
RNA primers on the lagging strand.
c.
RNA primers on both the lagging and leading strand.
d.
short lengths of new DNA on the lagging strand.
e.
RNA primers on the leading strand.
42. During DNA replication, the ____ strand is assembled in the ____ direction that the DNA double helix
unwinds and is produced by ____ replication.
a.
leading; opposite; continuous
b.
lagging; same; discontinuous
c.
leading; same; discontinuous
d.
lagging; opposite; continuous
e.
leading; same; continuous
43. In eukaryotes the DNA molecule that makes up a chromosome is typically ____ and usually has ____
replication origin.
a.
circular; one
b.
circular; more than one
c.
linear; more than one
d.
linear; one
e.
linear; no
44. The energy to form the new bond when a nucleotide is added to a growing DNA strand is provided
primarily by ____.
a.
unwinding of the DNA double helix
b.
hydrolysis of pyrophosphate
c.
breaking hydrogen bonds between base pairs
d.
DNA polymerase
e.
forming hydrogen bonds between base pairs
45. Imagine that a cell has a genetic mutation so that the primase enzyme is unable to make RNA strands.
Assuming that all of the other enzymes directly involved in DNA replication are still functional in
these cells, how much of the process of DNA replication would you expect to see in these cells?
a.
The leading strand would be synthesized, but not the lagging strand.
b.
None of it at all, no part of the DNA replication process could occur.
c.
The DNA helix would be unwound by helicase, but no new strands will be produced at all.
d.
Both the leading and lagging strand would be synthesized, but pieces of discontinuous
strands would not be joined together.
e.
DNA replication would still proceed completely, since RNA strands are not part of the
final product of DNA replication.
46. Telomeres are found
a.
in the middle of chromosomes.
b.
at replication origins.
c.
where DNA strands are joined together.
d.
within genes.
e.
at the ends of a chromosome.
47. In humans telomerase functions to
a.
add telomere repeats in some human cells.
b.
remove telomere repeats in all human cells.
c.
add telomere repeats in all human cells.
d.
remove telomere repeats in some human cells.
e.
transcribe telomere repeats in some human cells
48. During normal DNA replication, part of the DNA at the ends of linear chromosomes is not copied into
the new DNA strands because
a.
DNA ligase cannot join pieces at the end of a chromosome.
b.
RNA primers at the beginning of a new strand cannot be replaced with DNA.
c.
those ends are Okazaki fragments that are lost.
d.
cells do not need the DNA at the ends of chromosomes.
e.
the ends of chromosomes are made of protein, not DNA.
49. Suppose you take a cell from an adult cow and attempt to use it to produce a clone of that cow. If for
some reason telomerase is not functioning in that cell or in any cell that comes from it, what will you
expect to happen with your clone?
a.
The cell will never be able to divide at all.
b.
When the clone grows up, it will most likely have cancer.
c.
The cell may divide, but after a certain number of divisions, cell division will stop.
d.
The lack of telomerase should have no effect on the clone.
e.
When the clone grows up, it will most likely be sterile.
50. Fragile X syndrome is one of the most common sources of inherited ____.
a.
sterility
b.
mental retardation
c.
blindness
d.
cancer
e.
deafness
51. Fragile X syndrome is caused by ____ on the X chromosome in humans.
a.
the presence of CCG repeats
b.
mutations within CCG repeats
c.
deletion of CCG repeats
d.
overreplication of CCG repeats
e.
the absence of CCG repeats
52. Many errors made during DNA replication are corrected during DNA replication through proofreading
by ____.
a.
DNA polymerase
b.
primase
c.
telomerase
d.
DNA ligase
e.
helicase
53. Without proofreading, the rate of errors in DNA replication in bacteria is as high as about one for
every ____ nucleotides assembled.
a.
10 to 100
b.
100,000 to 1,000,000
c.
1000 to 10,000
d.
10,000,000 to 100,000,000
e.
100,000,000 to 1,000,000,000
54. DNA repair enzymes typically find mismatched base pairs by scanning for ____.
a.
missing hydrogen bonds
b.
unsealed nicks in the DNA strands
c.
Okazaki fragments
d.
extra hydrogen bonds
e.
distortions in the DNA double helix
55. After DNA repair enzymes cut out part of a DNA strand that had an incorrect nucleotide, ____ is/are
needed to complete the repair.
a.
primase, DNA polymerase, and DNA ligase
b.
DNA polymerase
c.
DNA polymerase and DNA ligase
d.
primase and DNA ligase
e.
primase and DNA polymerase
56. Individuals with xeroderma pigmentosum inherit a faulty DNA repair mechanism. As a consequence,
they
a.
are sterile.
b.
have no proofreading during DNA replication.
c.
cannot join the Okazaki fragments produced during DNA replication.
d.
easily develop skin cancer when exposed to sunlight.
e.
lose part of the DNA on the ends of chromosomes during each round of DNA replication.
57. ____ are the ultimate source of variability in offspring.
a.
Mutations
b.
Nucleosomes
c.
Okazaki fragments
d.
DNA repairs
e.
RNA primers
58. Chromatin is made up of
a.
DNA only.
b.
DNA, RNA, and protein.
c.
DNA and RNA.
d.
RNA and protein.
e.
DNA and protein.
59. Nucleosomes are best described as
a.
prokaryotic DNA associated with nonhistone proteins.
b.
eukaryotic DNA associated with histone proteins.
c.
prokaryotic DNA associated with histone proteins.
d.
eukaryotic DNA associated with nonhistone proteins.
e.
associated histone and nonhistone proteins
60. Histones are ____ and _________ proteins.
a.
large; negatively charged
b.
large; positively charged
c.
small; positively charged
d.
small; negatively charged
e.
large; uncharged
61. The DNA in the nucleus of a typical human cell nucleus would be about ____ long if fully stretched
out.
a.
2 m
b.
10 mm
c.
100 m
d.
10 m
e.
2 km
62. The electron micrograph above shows chromatin organized like “beads on a string.” At this level of
DNA compaction the “beads” are ____ and the “string” is ____.
a.
nucleosomes; DNA
b.
30-nm chromatin fibers; 10-nm chromatin fiber
c.
DNA; 10-nm chromatin fiber
d.
nucleosomes; histone H1
e.
DNA; histone H1
63. Association of histone H1 with linker DNA is required to form ____.
a.
heterochromatin
b.
the 10-nm chromatin fiber
c.
nucleosomes
d.
the solenoid
e.
euchromatin
64. The nucleosome core particle is composed of ____.
a.
DNA
b.
helicase
c.
single-stranded binding proteins
d.
RNA primer
e.
histones
65. Which of these items associated with DNA packaging is the thickest?
a.
a DNA double helix
b.
a solenoid
c.
a nucleosome
d.
an H2A histone protein
e.
an H1 histone protein
66. Histones bond to DNA by ____ of DNA.
a.
an ionic attraction to the phosphate groups
b.
hydrogen bonding to the deoxyribose sugars
c.
an ionic attraction to the nitrogenous bases
d.
hydrogen bonding with the nitrogenous bases
e.
covalent bonds to the deoxyribose sugars
67. The Barr body found in mammalian females is an X chromosome compacted to the level of ____.
a.
euchromatin
b.
10-nm chromatin fibers
c.
heterochromatin
d.
nucleosomes
e.
solenoids
68. In prokaryotes the DNA molecule that makes up a chromosome is typically ____ and usually has ____
replication origin.
a.
circular; one
b.
circular; more than one
c.
linear; more than one
d.
linear; one
e.
linear; no
69. Studies of human egg formation have shown that at ovulation the egg cell is stuck in metaphase II and
only completes meiosis if a sperm enters the egg. In metaphase II, chromosomes are tightly condensed,
so you should expect to find ____ in human egg cells that have not been entered by sperm.
a.
very high levels of gene expression
b.
mostly euchromatin
c.
very little gene expression
d.
no nucleosomes
e.
no solenoids
70. Cancer cells
a.
maintain telomerase function
b.
have longer telomeres than normal cells
c.
eventually die due to shortening chromosomes
d.
have circular chromosomes
e.
cannot replicate their DNA
71. Suppose that you performed a version of the Hershey and Chase experiment, this time using 32P-
labeled viruses that insert their double stranded DNA into the DNA of the cells that they infect. The
viral DNA is then treated as part of the cell’s own DNA and is replicated during DNA replication and
passed on to daughter cells when the cell divides. You infect a population of cells with the 32P-labeled
viruses, then let the infected cells go through two generations of cell divisions. If you then examine the
cells, you should find 32P-labeled DNA in
a.
none of them.
b.
about of them.
c.
about of them.
d.
about of them.
e.
all of them.
311
72. Suppose that a mistake made during DNA replication in a cell is not corrected, but instead the
mutation remains in the single strand where it occurred. Then suppose that after the cell divides both
daughter cells survive, and those cells then go on to have DNA replication and ultimately cell division.
There are now four cells where there once was one cell. Assuming that the mistake was never
corrected and that no new uncorrected mistakes occurred, how many of the four cells will have the
mutation in their DNA?
a.
none
b.
one
c.
two
d.
three
e.
four
MATCHING
Classification
For the following question(s), identify the researcher or researchers associated with the discovery or
experiment from the list below.
a.
Watson and Crick
b.
Avery, MacLeod, and McCarty
c.
Griffith
d.
Hershey and Chase
e.
Meselson and Stahl
73. Showed that DNA is the transforming principle from heat-killed S strain Streptococcus pneumoniae
that can make the R strain virulent
74. Showed that DNA replication in Escherichia coli is semiconservative
75. Showed that a transforming principle from heat-killed S strain Streptococcus pneumoniae could be
used to make the R strain virulent
76. Worked out the double helix model for DNA structure
77. Showed that the genetic material of bacteriophage T2 is DNA
SHORT ANSWER
78. More than 90% of cancer cells have fully active telomerase enzymes. Explain how that might play a
role in enabling cancer cells to keep rapidly dividing.
79. Acyclovir is a chemical analog of a DNA nucleoside that is used to treat people who are infected by
herpes simplex viruses (HSV). How does acyclovir work as a treatment without harming the patients?
80. Avery, MacLeod, and McCarty showed that DNA was the transforming principle when they mixed
dead virulent bacteria and live avirulent bacteria after treating with a DNA degrading enzyme, injected
this into mice, and observed that the mice survived. If RNA were the genetic material, what would
have been the effect on the mice after treating with a DNA degrading enzyme and why?
81. In the Meselson-Stahl experiment, DNA containing one heavy and one light strand was observed after
one generation of growth in media containing light nitrogen. If they had not allowed a second
generation of growth, what would these scientists have been able to conclude?
82. What are two main reasons why DNA replication is so error-free?
ESSAY
83. Describe the roles of the following enzymes during DNA replication: ligase, single-stranded binding
protein (SSB), DNA polymerase III, primase, DNA helicase.
84. Describe how DNA packing occurs in eukaryotes using the terms nucleosome, 30 nm fiber,
euchromatin, and heterochromatin. Then describe how DNA is packed in prokaryotes.
85. Although Watson and Crick are credited with the discovery of the structure of DNA, they based this
discovery on the bench work of many other scientists of the time. Name at least three different pieces
of knowledge that Watson and Crick used in their discovery that was based on work from someone
else.