Deck 15: Regulation of Gene Expression in Bacteria and Bacteriophages

Question 1

What procedure would you use to detect a nutritional mutation in microorganisms?

A) Isolation at high temperature
B) Controlled crosses
C) Plating on antibiotic-containing medium
D) Replica plating
E) Visible inspection

Answer 1

D

Question 2

What is conservative transposition?

A) Transposition without disruption of normal gene product activity
B) No net increase in the number of transposable elements in the genome
C) Movement of transposable elements without replication of the element
D) A net increase in the number of transposable elements in the genome
E) Movement of transposable elements with replication of the element

Answer 2

C

Question 3

How do mutations occur?

A) Bases may be mispaired during replication.
B) Base changes may occur spontaneously.
C) Environmental mutagens may alter a base.
D) Adaptation to environmental influences
E) All of the above but D

Answer 3

E

Question 4

The deamination of cytosine creates

A) uracil.
B) 5-bromouracil.
C) 5-methyl cytosine.
D) 2-aminopurine.
E) thymine.

Question 5

Spontaneous mutation rates are greatly reduced by

A) reverse mutations.
B) DNA repair mechanisms.
C) base-modifying agents.
D) exposure to ionizing radiation.
E) performing the Ames test.

Question 6

The mutation rate refers to

A) the probability of a particular mutation over time.
B) the rate of spontaneous mutations that are not repaired by DNA repair mechanisms.
C) the ability of mutations to be transmitted from one generation to the next.
D) the number of occurrence of a particular mutation per number of cells or individuals in a population.
E) both A and B.

Question 7

Which of the following transposable elements are found in eukaryotes BUT NOT in prokaryotes?

A) IS elements
B) Retrotransposons
C) Families of autonomous and nonautonomous elements
D) Ty elements
E) All but A

Question 8

A mutation during DNA replication causes a G to be inserted after the first base of the codon for tryptophan. How will this affect the growing polypeptide chain?

A) It will not be affected.
B) There will be a single amino acid substitution.
C) Elongation will stop prematurely.
D) The reading frame will be shifted to the left, and the wrong amino acids will be added from this point on.
E) An extra amino acid will be added, but the reading frame will not be affected.

Question 9

Which of the following is NOT mutagenic?

A) AZT
B) nitrous acid
C) hydroxylamine
D) 5BU
E) acridine

Question 10

A transition mutation is one that results in a switch from a ________ base pair to a ________ base pair.

A) pyrimidine-purine, pyrimidine-purine
B) purine-pyrimidine, purine-pyrimidine
C) pyrimidine-purine, purine-pyrimidine
D) purine-pyrimidine, pyrimidine-purine
E) Both A and B

Question 11

Thymine dimers are commonly caused by

A) tautomers.
B) ionizing radiation such as X-rays.
C) intercalating agents.
D) ultraviolet radiation.
E) alkylating agents.

Question 12

Base analogs may cause mutations because

A) they modify the chemical structure and properties of the normal base.
B) they may exist in alternate chemical states that pair with different DNA bases than the normal state during replication.
C) they insert themselves between adjacent bases on the DNA strand and cause an extra base to be inserted during replication.
D) they remove amino groups from bases, causing them to pair with the wrong base during replication.
E) Both A and C

Question 13

Xeroderma pigmentosum is a human genetic disease caused by

A) elevated levels of cholesterol in the blood.
B) loss of genes controlling the SOS response.
C) mutations that inactivate tumor suppressor genes.
D) failure to produce pigment that protects the skin cells from UV light exposure.
E) defective DNA excision-repair mechanisms.

Question 14

Dissociation elements (Ds) in plants are examples of

A) repeated sequences that are targeted by a transposase.
B) nonautonomous elements that require activation by an autonomous element.
C) mutator genes that increase the spontaneous mutation frequencies of other genes.
D) activator transposons that can direct their own transposition.
E) Both B and C

Question 15

Genetic manipulation in Drosophila may be assisted by the use of

A) Ty elements.
B) F factor.
C) P elements.
D) bacteriophage Mu.
E) Tn10.

Question 16

An IS (insertion sequence) element contains

A) a transposase gene and inverted repeats at the ends.
B) a transposase gene only.
C) a transposase gene, additional genes, and inverted repeats at the ends.
D) genes but not a transposase gene.
E) a transposase gene and additional genes.

Question 17

A transposon is

A) a mobile genetic element that may or may not leave a copy of itself in its original site when it moves to a new site.
B) a DNA segment that can insert itself at one or more sites in a genome.
C) a DNA segment that may cause mutations in genes or chromosomal rearrangements.
D) a "jumping gene."
E) All of the above

Question 18

Barbara McClintock's contemporaries were hostile to her discovery of mobile genetic elements because

A) she used unconventional laboratory techniques.
B) her previous contributions to cytogenetics had not been recognized.
C) her experimental data did not support her interpretations.
D) her ideas were in contradiction to the accepted model of a static arrangement of genes on chromosomes.
E) she was a woman in a man's world.

Question 19

In order for the Ds mutations in corn to be stable,

A) an Ac element must not be present.
B) an Ac element must be present.
C) the Ds must contain the gene for transposition.
D) the DNA must not be replicated.
E) None of the above

Question 20

How does the DNA mismatch-repair mechanism in bacteria recognize which base is the correct one (i.e., the template strand) following DNA replication?

A) The Uvr protein complex recognizes an adjacent pyrimidine dimer.
B) The mismatch distorts the shape of only the newly synthesized DNA strand.
C) The incorrect base is methylated immediately after DNA replication.
D) The mismatch correction enzyme recognizes the unmethylated state of the newly synthesized DNA segment.
E) The mechanism is unknown.

Question 21

A tautomer is an uncommon form of DNA base that naturally exists along with the common form.

Question 22

Describe how the Ames test is used to determine whether a particular chemical is mutagenic.

Question 23

Explain how IS elements produce target-site duplications when they move.

Question 24

The DNA polymerase proofreading mechanism maintains a low mutation rate in eukaryotic genes.

Question 25

What is a retrotransposon, and how does it differ from typical transposons?

Question 26

What kind of mutation detection procedure can be used to detect the white eye mutation in Drosophila?

Question 27

Deaminating agents alter DNA by the addition of a hydroxyl group to one of the bases.

Question 28

How does an intercalating agent such as ethidium bromide cause mutations?

Question 29

A point mutation changes a codon from UCG to UAG. What will happen to the resulting polypeptide?

Question 30

5-bromouracil (5BU) is a mutagen because it is an analog of the base thymine and may pair with guanine instead of adenine if it is incorporated into a DNA strand.

Question 31

Barbara McClintock discovered that a controlling element was responsible for the mutant spotted phenotype (purple spots on white) in corn kernels. Explain how this works.

Question 32

Changes in heritable traits result from adaptation to environmental influences.

Question 33

LINEs and SINEs are repetitive sequences in humans that are also retrotransposons that can insert into genes and cause disease.

Question 34

Composite transposons contain a central region with genes and repeated sequences at their ends but do not terminate with IS elements.

Question 35

A transposon may carry genes for proteins that enable their transposition, as well as genes for other functions such as drug resistance.

Question 36

Somatic mutations may be inherited by the next generation.

Question 37

How can PCR be used to induce site-specific mutations in DNA?

Question 38

A tumor suppressor gene is cloned and mutagenized in vitro, then injected into mouse embryos to create knockout mice. How could you identify the heterozygous knockout mice and create mice susceptible to tumors?

Question 39

How does the nucleotide excision repair (NER) system in E. coli work, and what kinds of DNA damage does it repair?

Question 40

What are two ways that a reverse mutation can occur?

Question 41

How can mutant organisms assist scientists in understanding how normal physiological processes take place?

Question 42

Explain what a mutator gene is and give an example.