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LESSON - 26
DNA: THE GENETIC MATERIAL.
A. Objectives
-
Use the Hammerling, Griffith-Avery, Hershey-Chase, and FraenkelConrad experiments
to argue that genetic material is present in the nucleus, is DNA (and 1RNA in RNA
viruses); design analogous experiments to argue the same points; explain why Griffith
and Avery did not conclude that RNA was the genetic material of bacteria.
Draw and explain the structure of a nucleotide and nucleic acid strand; properly number
the carbon atoms of the pentose; explain the direction of a nucleic acid strand.
List, explain and use Chargaff’s rules of base pairing; tell what Franklin’s contribution
was to unraveling the DNA structure; give an account of the structure of the DNA
molecule; list alternative structures that fulfil Chargaff’s rule and discuss why they are
not likely correct.
Know who and when the structure of the DNA molecule was unraveled.
B.
Lecture outline
1.
DNA IS THE GENETIC MATERIAL
Read:
a.
b.
c.
d.
Acetabularia and the control of cell activities (SBM p86-87)
DNA is the transforming principle in bacteria (SBM p261-262)
DNA is the genetic material in certain viruses SBM p263)
Genetic information is stored in the nucleus (J. Hammerling and J. Brachet, 1930)
the Fred Griffith (1928)-Oswald Avery (1944) experiment: bacteria
the Herschey—Chase experiment (1952): DNA viruses
the Fraenkel—Conrad experiment (1954): RNA viruses
LESSON - 27
DNA: DISCOVERY OF THE STRUCTURE.
A. Objectives
-
Draw and explain the structure of a nucleotide and nucleic acid strand; properly number
the carbon atoms of the pentose; explain the direction of a nucleic acid strand.
List, explain and use Chargaff’s rules of base pairing; tell what Franklin’s contribution
was to unraveling the DNA structure; give an account of the structure of the DNA
molecule; list alternative structures that fulfil Chargaff’s rule and discuss why they are
not likely correct.
Know who and when the structure of the DNA molecule was unraveled.
B.
Lecture outline
2.
THE STRUCTURE OF DNA
Read:
The Structure of DNA (SBM p263-266)
a.
nucleotides, nucleic acid revisited
b.
the DNA molecule
- Chargaff’s rules (1948)
-
X-ray crystallography (Rosalind Franklin, 1953)
 Two parallel strands (2 nm wide)
 Helical
 10 nucleotides per turn (periodicity of 34 nm)
-
the double helix (Watson and Crick, 1953)
C. Study Questions.
1.
In what period were Hammerlings work published?
A.
l700s.
B.
1800s.
C.
1930s.
D.
1950s.
E.
1970s.
2.
The organism Hammerl.ing worked with was a member of the
A. viruses.
B.
plants.
C.
algae.
D.
fungi.
E.
bacteria.
3.
Acetabularia are organism best described as
A. unicellular, photo-litho- C-autotrophs.
B.
multicellular, photo-litho- C-autotrophs.
C.
unicellular, chemo- organo- C-heterotrophs.
D. multicellular, chemo-organo- C-heterotrophs.
4.
Hammerling’s experiments strongly suggested that
A.
DNA is the genetic material.
B.
DNA is the genetic material of bacteria.
C.
DNA is the genetic material of eukaryotes.
D. DNA is the genetic material of DNA viruses.
E.
the genetic material is contained in the nucleus ofeukaryotic cells.
5.
Select the chimaeric organism(s) that will grow a cap of A. crenata.
foot cell
nucleus
A.
B.
C.
D.
E.
A. mediteranea
A. mediteranea
A. crenata
A. mediteranea
A. crenata
6.
Fred Griffith worked in England in the
A.
1900s.
B.
1920s.
C.
1940s.
D.
1960s.
E.
1980s.
7.
Griffith’s experiments were done with
A. Ace tabularia mediteranea.
B.
Tobacco mosaic virus.
C.
Streptococcus pneumoniae.
D. frog embryos.
E.
human babies
A. mediteranea
A. crenata
A. mediteranea
A. mediteranea
A. mediteranea
8. The bacteria that Griffith worked with killed mice only if they had
A. been isolated from diseased mice.
B. heat-killed.
C.
a cell wall rich in pept idoglycan.
D. a polysaccharide—rich capsule.
stalk
A. mediteranea
A. mediteranea
A. mediteranea
A. crenata
A. crenata
E.
a visible nucleus.
9.
In Griffith’s experiments, avirulent bacteria changed and caused disease when they were mixed with
A. dead mice.
B.
dead, virulent bacteria.
C.
bacteria isolated from sick mice.
D. DNA from mice that had died from the bacterial disease.
E.
DNA from other avirulent bacteria.
10.
When the avirulent bacteria changed to virulent organisms in Griffith’s experiments, they were said to be A.
killed.
B.
potentiated.
C.
reactivated.
D.
virulated.
E.
transformed.
11.
Predict which injection(s) of the Griffith’s experiments will kill the injected mice. Injection with
A.
live, avirulent, non— encapsulated bacteria.
B.
heat—killed, virulent, encapsulated bacteria.
C.
heat-killed, avirulent, non-encapsulated bacteria.
D.
live, avirulent, non— encapsulated bacteria AND heat— killed, virulent, encapsulated bacteria.
E.
live, avirulent, non— encapsulated bacteria AND heat— killed, avirulent, non— encapsulated
bacteria.
F.
live, virulent, encapsulated bacteria AND heat-killed, avirulent, non—encapsulated bacteria.
12.
Oswald Avery and his collaborators showed that the ‘transforming principle’ of Griffith was
A.
bacterial DNA.
B.
mouse DNA.
C.
capsular polysaccharide.
D.
bacterial enzymes.
E.
lipopolysaccharides.
13.
The work of Oswald Avery and coworkers was published in
A.
1886.
B.
1928.
C.
1944.
D.
1948.
E.
1953.
14.
The works of Griffith and Avery showed that
A.
DNA is the genetic material.
B.
DNA is the genetic material of bacteria.
C.
DNA is the genetic eukaryotes.
D.
DNA is the genetic DNA viruses.
E.
the genetic material is contained in the nucleus of eukaryotic cells.
15.
What radioactive isotope would you select to label only the proteins of a virus (explain why!)?
A.
carbon (14C).
B.
phosphorus (32P).
C.
nitrogen (15 N).
D.
oxygen (180).
E.
sulfur (35S).
16.
What radioactive isotope would you select to label only the nucleic acid of a virus (explain why!)?
A.
carbon (14C).
B.
phosphorus (32P)
C.
nitrogen (15N).
D.
E.
oxygen (180).
sulfur (35S).
17.
The radioactive material injected into the bacteria by the bacteriophages of Hershey—Chase was
A.
carbon (14C).
B.
phosphorus(32P).
C.
nitrogen (15N).
D.
oxygen (180).
E.
sulfur (35S).
18.
The radioactive material injected into the bacteria by the bacteriophages of Hershey-Chase indicated that
A.
DNA, not protein is the genetic material.
B.
protein is not an important part of the virus.
C.
DNA is not an important part of the virus.
D.
the bacterial cells had more need for P than for S.
E.
only P is needed to make new virus particles.
19.
The Hershey—Chase experiment was published in
A.
the 1940s.
B.
1952.
C.
1953.
D.
1957.
E.
1960s.
20.
The plant viruses TMV and HRV both consist of a helical capsid and a
A.
single strand of DNA.
B.
double strand of DNA.
C.
double strand of RNA.
D.
single strand of RNA.
E.
strand of DNA and RNA.
21.
The Fraenkel-Conrat (1958) experiments with the plant viruses, TMV and HRV, concluded that the hereditary
properties of (RNA)viruses are determined by
A.
enzymes produced by the plants in response to the virus infection.
B.
enzymes produced by the virus after infection of the plants.
C.
the nucleic acid of the virus, in this case RNA.
D.
the nucleic acid of the virus,in this case DNA.
E.
the information embedded in the viral protein capsid.
22.
Nucleotides have a nitrogen—containing base attached to a sugar at the carbon labeled
A.
1’
B.
2’
C.
3’
D.
4’
E.
5’
23.
Nucleotides have a phosphate group attached to a sugar at the carbon labeled
A.
1’
B.
2’
C.
3’
D.
4’
E.
5’
24.
To what carbon is the hydroxyl-group connected that reacts with the phosphate—group of another nucleotide
to form a polymer?
A.
B.
C.
D.
E.
1’
2’
3’
4’
5’
25.
The bond that connects the nucleotides in a nucleic acid strand is a
A.
C=C double bond.
B.
hydrogen bond.
C.
unsaturated bond.
D.
peptide bond.
E.
phosphodiester.
26.
In reciting a list of bases along the length of a nucleic acid strand we proceed in the direction of the
A.
1’ end.
B.
2’ end.
C.
3’ end.
D.
4’ end.
E.
5’ end.
27~ Identify Chargaff’s rule(s).
A.
A=C and G=T.
B.
A=G and C=T.
C.
(A + G) = (C + G).
D.
purines = pyrimidines.
E.
A=T and G=C.
28.
Chargaffs rules involve the
A.
relative presence of N—bases in DNA.
B.
three—dimensional structure of DNA.
C.
structure of nucleotides.
D.
position of the sugar-phosphate backbones in the molecule.
E.
specific pairing of the bases in DNA.
29.
Chargaffs rules were published in
A.
1944.
B.
1947.
C.
1948.
D.
1952.
E.
1953.
30.
X-ray crystallography is a procedure for determining the
A.
three—dimensional structure of a molecule.
B.
nature of the chemical elements present in a molecule.
C.
“health” of a molecule, i.e., whether the molecule is normal or abnormal.
D.
sequence of bases along the length of a molecule.
E.
size (molecular weight) of a molecule.
31.
X-ray crystallography suggested to Rosalind Franklin and Maurice Wilkins that the DNA molecule is a
A.
fiber.
B.
flat sheet.
C.
helix with a periodicity of 3.4 nm.
D.
long thread.
E.
spherical globule.
32.
The two strands of a DNA molecule are held together by
A.
A. C=C double bond. B. hydrogen bond.
C.
D.
E.
unsaturated bond.
peptide bond.
phosphodiester.
33.
The relationship between the base sequence of the two strands of a DNA molecule is
A.
complementary.
B.
conservative.
C.
cooperative.
D.
liberal.
E.
opposite.
34.
The two strands of a DNA molecule are said to be opposite. To what property of the DNA molecule does this
characteristic refer?
A.
Position of the phosphate- and hydroxy 1-groups.
B.
Direction.
C.
Base sequence.
D.
Handedness of the helical turns.
E.
Base pairing.
35.
The notation PA-A-T-C-C-G-TOH represents a nucleic acid strand of a DNA molecule in which A, T, C, and G
are the nucleotides and “P”“ and “OH” are the free phosphate- and hydroxyl group, respectively. What is the
nucleotide sequence of the complementary strand?
A. PA-A-T-C-C-G-TOH
B. PT-T-A-G-G-C-AOH
HO
c.
T-T-A-G-G-C-AP
P
D.
A-A-T-C-C-G-TOH
HO
E.
C-C-G-A-A-T-GP
36.
If the base—pairing rules are followed, then in a double helix of DNA the amount of
A. A=Gand C=T.
B. A + (T/G) + C = 1.
C. (A+T) = (G+C).
D. (A + G)/(C + T) = 1
E.
(A + C) = (G + T).
37.
Identify the scientist whose X-ray diffraction studies of DNA provided important information regarding the
structure of DNA.
A.
Crick.
B.
Hammerling.
C.
Mendel.
D.
Franklin.
E.
Chargaff.
Which researchers identified DNA as• the genetic material of bacteriophages?
A.
Watson and Crick.
B.
Herschey and Chase.
C.
Griffith and Avery.
D. Meselsohn and Chase.
E.
Fraenkel and Conrad
38.
39.
Which researchers correctly identified the structure of DNA?
A.
Watson and Crick.
B.
Mieschner and Levinson.
C.
Franklin and Wilkins.
D. Griffith and Avery.
E.
Fraenkel and Conrad.
40.
Thirty percent of the bases in DNA of the bacterium Pseudomonas is adenine. What percentage of cytosine is
present in this DNA?
A.
10.
B.
20.
C.
30.
D. 40.
E.
60.
41.
Consider the following DNA strand: 5 • TACCGCCTATACT3. What is the purine/pyrimidine ratio of the
intact double helix?
A.
0.45
B.
0.85
C.
1
D.
1.25
E.
1.45
42. In the classic experiments by Bracht and Hammerling, the nucleus of Acetabularia was removed, the cap was cut
off, a nucleus of a different species was inserted, and the cap was allowed to regenerate. The new cap was then
removed. After the second regeneration, the cap was observed, and the following conclusion was made:
A. The shape of the cap was controlled by the nucleus, thus, the nucleus was the control center of the
cell.
B. The shape of the cap was under the control of the stalk, which produced a control substance.
C. The shape of the cap was independent of both the stalk and the holdfast.
D. The “cren” caps were defective due to some mutation in the cap. Thus, “cren” caps are independent
of control from both the base and the holdfast.
E. At the time no conclusion could be made because in the early 20th century, biologists did not know
about the composition of DNA.
43. The main reason scientists thought that proteins, rather than DNA, were the carriers of genetic material in the
cell was:
A.
B.
C.
D.
E.
their presence within the nucleus.
their abundance within the cell.
the large number of possible amino acid combinations.
their ability to self replicate within the cytoplasm.
their ability to be exported from the cell.
44. In the experiments of Griffith, the conversion of nonlethal R-strain bacteria to lethal S-strain bacteria:
A.
B.
C.
D.
E.
was the result of genetic mutation.
was an example of the genetic exchange known as transformation.
supported the case for proteins as the genetic material.
could not be reproduced by other researchers.
was an example of conjugation.
45. The first experimenters to use Griffith’s transformation assay to identify the genetic material were:
A.
B.
C.
D.
E.
Meselson and Stahl.
Watson and Crick.
Franklin and Wilkins.
Avery, MacLeod, and McCarty.
Hershey and Chase.
46. Which of the following statements about DNA is false?
A.
B.
C.
D.
E.
DNA is capable of forming many different sequences.
DNA contains thymine instead of uracil.
DNA is double-stranded rather than single-stranded.
DNA is only found in eukaryotic cells.
DNA contains the sugar deoxyribose.
47. The bacteriophages used in Alfred Hershey’s and Martha Chase’s experiments showed that:
A.
B.
C.
D.
E.
DNA was injected into bacteria.
DNA and protein were injected into bacteria.
DNA remained on the outer coat of bacteria.
proteins were injected into bacteria.
proteins were responsible for the production of new viruses within the bacteria.
48. The two molecules that alternate to form the backbone of a polynucleotide chain are:
A.
B.
C.
D.
E.
adenine and thymine.
cytosine and guanine.
sugar and phosphate.
base and sugar.
base and phosphate.
49. Chargaff determined that DNA from any source contains about the same amount of guanine as __________.
A.
B.
C.
D.
E.
uracil
thymine
adenine
cytosine
guanine
50. ______________________ used x-ray diffraction to provide images of DNA.
A.
B.
C.
D.
E.
Watson and Crick
Crick and Wilkins
Franklin
Franklin and Crick
Watson and Wilkins
51. X-ray diffraction studies are used to determine:
A.
B.
C.
D.
E.
the sequence of amino acids in protein molecules.
the sequence of nucleic acids in nucleic acid molecules.
the distances between atoms of molecules.
the type of chemical under investigation.
the wavelength of light emitted by chemicals.
52. X-ray crystallography showed that DNA:
A.
B.
C.
D.
E.
had the bases in the center of the molecule.
had the sugars and phosphates on the outside of the molecule.
was a very long molecule.
was made of 2 strands.
was a helix.
53. ______________________ determined the structure of the molecule DNA.
A.
B.
C.
D.
E.
Crick and Wilkins
Watson and Crick
Franklin and Crick
Franklin
Watson, Crick, and Wilkins
54. The information carried by DNA is incorporated in a code specified by the:
A.
B.
C.
D.
E.
phosphodiester bonds of the DNA strand.
number of separate strands of DNA.
size of a particular chromosome.
specific nucleotide sequence of the DNA molecule.
number of bases in a DNA strand.
55. Why is DNA able to store large amounts of information?
A.
B.
C.
D.
E.
56-58.
questions.
It contains a large number of different nucleotides.
Its nucleotides can be arranged in a large number of possible sequences.
It is capable of assuming a wide variety of shapes.
The sugar and phosphates can be arranged in many different sequences.
The nucleotides can be altered to form many different letters in the sequence.
Use the figure to answer the corresponding
56. The portion of the molecule in box 5 of the accompanying
figure is:
A.
B.
C.
D.
E.
a hydrogen bond.
a phosphate.
a nucleotide.
a pyrimidine.
a protein.
57. In the figure, the portion of the molecule in box
pyrimidine.
A.
B.
C.
D.
E.
is a
1
3
4
1 and 3
3 and 4
58. The portion of the molecule in box 3 of the associated figure is:
A.
B.
C.
D.
E.
a sugar.
a protein.
a pyrimidine.
a purine.
a nucleotide.
59. Hydrogen bonds can form between guanine and ____________, and between adenine and ____________.
A.
B.
C.
D.
E.
phosphate; sugar
thymine; cytosine
cytosine; thymine
sugar; phosphate
adenine; guanine
60. Two chains of DNA must run in ____________ direction(s) and must be ____________ if they are to bond
with each other.
A.
B.
C.
D.
E.
the same; uncomplementary
opposite; uncomplementary
parallel; uncomplementary
parallel; complementary
antiparallel; complementary
61. Which of the following nucleotide sequences represents the complement to the DNA strand 5´ – AGATCCG3´?
A.
B.
C.
D.
E.
5´ – AGATCCG- 3´
3´ – AGATCCG- 5´
5´ – CTCGAAT- 3´
3´ – CTCGAAT- 5´
3´ – TCTAGGC- 5´
62. When Griffith injected mice with a combination of live rough-strain and heat-killed smooth-strain pneumococci,
he discovered that
A. the mice were unharmed
B. the dead mice contained living rough-strain bacteria
C. the dead mice contained living smooth-strain bacteria
D. DNA had been transferred from the smooth-strain bacteria to mice
E. DNA had been transferred from rough-strain bacteria to the smooth-strain bacteria
63. Which of the following inspired Avery and his colleagues to perform the experiments demonstrating that the
transforming principle in bacteria is DNA?
A. the fact that A is equal to T, and G is equal to C
B. Watson and Crick’s model of DNA structure
C. Meselson and Stahl’s studies on DNA replication in E.coli
D. Griffith’s experiments on smooth and rough strains of pneumococci
E. Hershey and Chase’s experiments on the reproduction of bacteriophages
64. In the Hershey-Chase experiment with bacteriophages,
A. harmless bacterial cells permanently transformed into virulent cells
B. DNA was shown to be the transforming principle of earlier bacterial transformation experiments
C. the replication of DNA was conclusively shown to be semiconservative
D. viral DNA was shown to enter bacterial cells and cause production of new viruses within the
bacteria
E. viruses inject their proteins, not their DNA, into bacterial cells
65. The two complementary strands of the DNA double helix are held to one another by
A. ionic bonds between deoyxribose molecules
B. ionic bonds between phosphate groups
C. covalent bonds between nucleotide bases
D. covalent bonds between deoxyribose molecules
E. hydrogen bonds between nucleotides
66. If a segment of DNA is 5’—CATTAC—3’, the complementary DNA strand is
A. 3’—CATTAC—5’
B. 3’—GTAATG—5’
C. 5’—CATTAC—3’
D. 5’—GTAATG—3’
E. 5’—CATTAC—5’
67. Each DNA strand has a backbone that consists of alternating
A. purines and pyrimidines
B. nucleotide bases
C. hydrogen bonds and phsophodiester linkages
D. deoxyribose and phosphate
E. phosphate and phosphodiester linkages