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General
---------Biology------------------------------------------- ------------------Online------------------------------------------------ |
1. What does transformation involve in bacteria? Pick the most
inclusive answer.
a. the creation of a strand of DNA from an
RNA molecule
b. the creation of a strand of RNA from a
DNA molecule
c. the infection of cells by a phage DNA molecule
d. the type of semiconservative replication
shown by DNA
e. the transfer of DNA into the cell, giving
the cell new genetic abilities.
2. What happens when T2 phages are grown with radioactive phosphorous?
a. Their DNA becomes radioactive.
b. Their proteins become radioactive.
c. Their DNA is found to be ionozed by the presence
of the isotope..
d. They are no longer able to transform bacterial
cells.
e. They transfer their radioactivity to carbohydrates
in the phage cytoplasm..
3. In the following list of DNA properties, which one would be
impossible for a single-stranded DNA molecule?
a. replication
b. information storage
c. exchange with other organisms
d. repair of thymine dimers
e. mutation
------------------------------
Refer to the list of enzymes shown below to answer the following
questions. The answers may be used once, more than once, or not
at
all.
a. helicase
b. exonuclease
c. ligase
d. polymerase
e. primase
4. Catalyzes synthesis of a new strand of DNA.
5. Enhances separation of DNA strands during replication.
6. Covalently connects segments of DNA.
7. Synthesizes short segments of RNA to allow polymerase to begin
dehydration synthesis.
8. The problem of replicating the lagging strand (that is, adding
bases
in the 3'--> 5' direction) is solved by DNA through
the use of
a. base-pairing of nucleotides.
b. replication forks.
c. the unwinding enzyme, helicase.
d. synthesis of Okazaki fragments.
e. RNA's use of Uracil rather than Thymine.
9. All of the following elements are present in DNA EXCEPT
a. oxygen.
b. nitrogen.
c. carbon.
d. sulfur.
e. phosphorus.
10. ALL OF THE FOLLOWING were directly provided by X-ray diffraction
photographs of crystallized DNA EXCEPT
a. the diameter of the double helix.
b. the helical shape of DNA.
c. the specificity of base pairing
d. the linear distance required for one full
turn of the double
helix.
e. the width of the helix.
11. What kind of chemical bonds are found between paired bases
of the
DNA double helix?
a. hydrogen
b. ionic
c. covalent
d. sulfhydryl
e. phosphate
12. What is the primer that is required to initiate the synthesis
of a new DNA strand?
a. RNA
b. DNA
c. protein
d. ligase
e. primase
13. Which enzyme catalyzes the elongation of a DNA strand in the
5'-->
3' direction?
a. primase
b. DNA ligase
c. DNA polymerase
d. topoisomerase
e. helicase
14. Which of the following descriptions best fits the class of
molecules
known as nucleotides?
a. a nitrogen base and a phosphate group only
b. a nitrogen base and a five-carbon sugar
only
c. a nitrogen base, a phosphate group, and
a five-carbon sugar
d. a five-carbon sugar, a phosphate group,
and a purine
e. a pyrimidine, a purine, and a six-carbon
sugar
------------------------------
Refer to the information given below to answer the following
question(s).
For each of the important discoveries that led to our present
knowledge of the nature of genes described below, select the
investigator(s) associated with each.
a. Griffith
b. Hershey
and Chase
c. Avery,
MacLeod, and McCarty
d. Chargaff
e. Meselson
and Stahl
15. Chemicals from heat-killed S cells were purified. The chemicals
were tested for the ability to transform live
R cells. The
transforming agent was found to be DNA.
16. The DNA of a phage was injected into the bacterial host, but
the
protein coat stayed outside. The viral DNA directed
the host to
replicate new phage viruses.
17. When T2 phage viruses that infect bacteria make more viruses
in the
presence of radioactive sulfur, which of the
following results?
a. The viral DNA is tagged by radioactivity.
b. The viral proteins are tagged by radioactivity.
c. The lipids are made radioactive.
d. None of their radioactivity is transfered
to E. coli cells.
e. Both the viral DNA and the viral proteins
are tagged by
radioactivity.
18. Suppose one were provided with an actively dividing culture
of E.
coli bacteria to which radioactive thymine
had been added. What
would happen if a cell replicated once in
the presence of this
radioactive base?
a. One of the daughter cells, but not the
other, would have
radioactive DNA.
b. Neither of the two daughter cells would
be radioactive.
c. All four bases of the DNA would be radioactive.
d. Radioactive thymine would pair with nonradioactive
guanine.
e. DNA in both daughter cells would be radioactive.
19. In DNA, the designations 3'and 5' refer to the
a. bonds formed between phosphate groups and
carbon atoms of
deoxyribose.
b. carbon or nitrogen atoms on the rings of purine
or pyrimidine
bases.
c. the number 3 and the number 5 carbons of the
sugar deoxyribose.
d. bonding between purines and deoxyribose and
between pyrimidines
and deoxyribose.
e. bonds that form between adenine and thymine
and between guanine
and cytosine.
------------------------------
Refer to Figure 15.1 to answer the following question(s).
| Recall the the isotope N15 has one more neutron than N14 and is |
| therefore heavier and would sink lower in the spinning centrifuge. |
Figure 15.1
20. In the Meselson-Stahl experiment, bacteria were grown in a
medium
containing 15N and were then transferred to a medium containing
14N. Which of the results in Figure 15.1 would be expected after
two DNA replication in 14N? 15N is an isotope of nitrogen and
contains one more neutron than 14N. It is heavier.
a. 1
b. 2
c. 3
d. 4
e. 5
21. What do genes do?
a. make proteins
b. make carbohydrates
c. make lipids
d. make cookies
e. make nice
22. In trying to determine whether DNA or protein was the genetic
material, Hershey and Chase made use of which
of the following
facts?
1. DNA
does not contain sulfur, whereas protein does.
2. DNA
contains phosphorus, but protein does not.
3. DNA
contains greater amounts of phosphorus than does
protein.
4. Protein
contains greater amounts of sulfur than does DNA.
a. 1
b. 2
c. 3
d. 4
e. Both 1 and 2 are correct.
23. Which of the following statements does not apply to the Watson
and
Crick model of DNA?
a. The two strands of the DNA helix are antiparallel.
b. The distance between the strands of the
helix is 20 angstroms.
c. The framework of the helix consists of
sugar-phosphate units of
the nucleotides.
d. The two strands of the helix are held together
by covalent bonds.
e. The purines are attracted to pyrimidines.
24. It became apparent to Watson and Crick after completion of
their
model that the DNA molecule could carry a
vast amount of hereditary
information in its
a. sequence of bases (nitrogenous bases).
b. phosphate-sugar backbones.
c. complementary pairing of bases.
d. side groups of nitrogenous bases.
e. different five-carbon sugars.
25. If radioactive sulfur (35S) is used in the culture medium
of
bacteria that harbor phage viruses, it will
later appear in the
a. viral DNA.
b. bacterial RNA.
c. viral protein coats.
d. viral RNA.
e. bacterial cell wall.
26. What is the function of DNA polymerase?
a. to unwind the DNA helix during replication
b. to seal together the broken ends of DNA
strands
c. to add nucleotides to the end of a growing
DNA strand
d. to repair damaged DNA molecules
e. to rejoin the two DNA strands (one new
and one old) after
replication
27. In an analysis of the nucleotide composition of DNA to see
which
bases are equivalent in concentration, which
of the following would
be true?
1. A = C
2. A = G and C = T
3. A + C = G + T
4. A + T = G + C
a. 1
b. 2
c. 3
d. 4
e. Both 2 and 3 are true.
28. DNA ligase functions in
a. elongation of the 5' --> 3' strand.
b. elongation of the 3' --> 5' strand.
c. covalent bonding of Okazawki fragments together.
d. unwinding of the double helix.
e. elongation of the 3' --> 5' strand AND
DNA repair.
29. When a double-stranded DNA molecule is heated, it denatures
into two
single-stranded molecules. The reason for
this is that
a. the proteins associated with the double
helix are denatured and
can no longer hold the DNA
strands together.
b. the heat causes the helix to straighten,
breaking the connections
between the phosphate in one
nucleotide and the sugar in the next..
c. the heat breaks the hydrogen bonds holding
the bases together in
the center of the molecule
but does not affect the covalent bonds
of the backbone.
d. the heat denatures the bases, preventing
them from
hydrogen-bonding with each
other.
e. the heat causes the phosphate groups to
ionize, preventing them
from hydrogen-bonding to
the bases.
30. Adenine and guanine have five nitrogen atoms; thymine has
two, and
cytosine has three. A DNA molecule from E.
coli has about 5 million
base pairs. If it were completely labeled
with 15N, how many
additional neutrons would that DNA have, compared
with a molecule
composed of normal 14N?
a. about 1 million
b. about 5 million
c. about 7.5 million
d. between 10 and 15 million
e. about 37.5 million
31. A DNA molecule consists of two strands of nucleotides. One
strand is
the information used by the cell, and the
other strand is a
complementary series of bases. This is analogous
to
1. a photograph and a photographic negative.
2. two sides of a divided highway.
3. a baseball and a bat.
4. an up escalator and a down escalator.
a. 1
b. 2
c. 3
d. 4
e. Both 2 and 4 are correct.
32. The two strands of a DNA molecule run in opposite directions.
The 3'
and 5' ends of one strand are opposite the
5' and 3' ends of the
complementary strand. This is analogous to
1. a photograph and a photographic negative.
2. two sides of a divided highway.
3. a baseball and a bat.
4. an up escalator and a down escalator.
a. 1
b. 2
c. 3
d. 4
e. Both 2 and 4 are correct.
33. For a couple of decades, we knew the nucleus contained DNA
and
proteins. The prevailing opinion was that
the proteins were the
genes and the DNA was a "string" that held
them together. The reason
for this belief was that
a. All of these are correct.
b. proteins take a greater variety of three-dimensional
forms.
c. proteins have four different levels of
structure; DNA has only
two.
d. proteins are made of 20 amino acids and
DNA is made of four
nucleotides.
e. proteins can vary in their polarity and
charge; DNA cannot.
Label the following figures, and use text figures to check your answers.
____34 nucleotide. ____35 hydrogen bonds. ____36 base pair.
____37 sugar. ____38. phosphate ____39. base pair (duplicate question)
____43. ligase ____44. primase
Discussion Questions:
One aspect of aging appears to be related to telomers. Every time
a chromosome is duplicated in the S Phase
of Interphase, the ends of the chromosome (i.e. telomers) unravel.
This sets a limite of around 50 cell divisions
before the chromosome unraveling effects genes.
Speculate on why Dolly the Sheep and other clones tend to die early?
Read the attached article
on cloning a cloned calf, and:
Explain the author's speculation on what must have happened to the calf's telomers.Why did the researchers wait to announce their results?
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