1) The role of a metabolite that controls a repressible operon is
to
A) bind to the promoter region and decrease the affinity of
RNA polymerase for the promoter.
B) bind to the operator region
and block the attachment of RNA polymerase to the promoter.
C)
increase the production of inactive repressor proteins.
D) bind
to the repressor protein and inactivate it.
E) bind to the
repressor protein and activate it.
e
2) The tryptophan operon is a repressible operon that is
A)
permanently turned on.
B) turned on only when tryptophan is
present in the growth medium.
C) turned off only when glucose is
present in the growth medium.
D) turned on only when glucose is
present in the growth medium.
E) turned off whenever tryptophan
is added to the growth medium.
e
3) Which of the following is a protein produced by a regulatory
gene?
A) operon
B) inducer
C) promoter
D)
repressor
E) corepressor
d
4) A lack of which molecule would result in the cells inability to
"turn off" genes?
A) operon
B)
inducer
C) promoter
D) ubiquitin
E) corepressor
e
5) Which of the following, when taken up by the cell, binds to the
repressor so that the repressor
no longer binds to the
operator?
A) ubiquitin
B) inducer
C) promoter
D)
repressor
E) corepressor
b
6) Most repressor proteins are allosteric. Which of the following
binds with the repressor to alter
its conformation?
A)
inducer
B) promoter
C) RNA polymerase
D) transcription
factor
E) cAMP
a
7) A mutation that inactivates the regulatory gene of a repressible
operon in an E. coli cell would
result in
A) continuous
transcription of the structural gene controlled by that
regulator.
B) complete inhibition of transcription of the
structural gene controlled by that regulator.
C) irreversible
binding of the repressor to the operator.
D) inactivation of RNA
polymerase by alteration of its active site.
E) continuous
translation of the mRNA because of alteration of its structure.
a
8) The lactose operon is likely to be transcribed when
A) there
is more glucose in the cell than lactose.
B) the cyclic AMP
levels are low.
C) there is glucose but no lactose in the
cell.
D) the cyclic AMP and lactose levels are both high within
the cell.
E) the cAMP level is high and the lactose level is low.
d
9) Transcription of the structural genes in an inducible
operon
A) occurs continuously in the cell.
B) starts when
the pathway's substrate is present.
C) starts when the
pathway's product is present.
D) stops when the
pathway's product is present.
E) does not result in the
production of enzymes.
b
10) For a repressible operon to be transcribed, which of the
following must occur?
A) A corepressor must be present.
B)
RNA polymerase and the active repressor must be present.
C) RNA
polymerase must bind to the promoter, and the repressor must be
inactive.
D) RNA polymerase cannot be present, and the repressor
must be inactive.
E) RNA polymerase must not occupy the promoter,
and the repressor must be inactive.
c
11) Allolactose, an isomer of lactose, is formed in small amounts
from lactose. An E. coli cell is
presented for the first time
with the sugar lactose (containing allolactose) as a potential
food
source. Which of the following occurs when the lactose
enters the cell?
A) The repressor protein attaches to the
regulator.
B) Allolactose binds to the repressor protein.
C)
Allolactose binds to the regulator gene.
D) The repressor protein
and allolactose bind to RNA polymerase.
E) RNA polymerase
attaches to the regulator.
b
12) Altering patterns of gene expression in prokaryotes would most
likely serve the organism's
survival in which of the
following ways?
A) organizing gene expression so that genes are
expressed in a given order
B) allowing each gene to be expressed
an equal number of times
C) allowing the organism to adjust to
changes in environmental conditions
D) allowing young organisms
to respond differently from more mature organisms
E) allowing
environmental changes to alter the prokaryote's genome
c
13) In response to chemical signals, prokaryotes can do which of the following?
A) turn off translation of their mRNA
B) alter the level of production of various enzymes
C) increase the number and responsiveness of their ribosomes
D) inactivate their mRNA molecules
E) alter the sequence of amino acids in certain proteins
b
14) In positive control of several sugar-metabolism-related operons,
the catabolite activator
protein (CAP) binds to DNA to stimulate
transcription. What causes an increase in CAP?
A) increase in
glucose and increase in cAMP
B) decrease in glucose and increase
in cAMP
C) increase in glucose and decrease in cAMP
D)
decrease in glucose and increase in repressor
E) decrease in
glucose and decrease in repressor
b
15) There is a mutation in the repressor that results in a molecule
known as a super-repressor
because it represses the lac operon
permanently. Which of these would characterize such
a
mutant?
A) It cannot bind to the operator.
B) It
cannot make a functional repressor.
C) It cannot bind to the
inducer.
D) It makes molecules that bind to one another.
E)
It makes a repressor that binds CAP.
c
16) Which of the following mechanisms is used to coordinate the
expression of multiple, related
genes in eukaryotic
cells?
A) A specific combination of control elements in each
gene’s enhancer coordinates the
simultaneous activation of the
genes.
B) The genes share a single common enhancer, which allows
appropriate activators to turn on
their transcription at the same
time.
C) The genes are organized into large operons, allowing
them to be transcribed as a single unit.
D) A single repressor is
able to turn off several related genes.
E) Environmental signals
enter the cell and bind directly to promoters.
a
17) If you were to observe the activity of methylated DNA, you would
expect it to
A) be replicating nearly continuously.
B) be
unwinding in preparation for protein synthesis.
C) have turned
off or slowed down the process of transcription.
D) be very
actively transcribed and translated.
E) induce protein synthesis
by not allowing repressors to bind to it.
c
18) Genomic imprinting, DNA methylation, and histone acetylation are
all examples of
A) genetic mutation.
B) chromosomal
rearrangements.
C) karyotypes.
D) epigenetic
phenomena.
E) translocation.
d
19) When DNA is compacted by histones into 10-nm and 30-nm fibers,
the DNA is unable to
interact with proteins required for gene
expression. Therefore, to allow for these proteins to act,
the
chromatin must constantly alter its structure. Which processes
contribute to this dynamic
activity?
A) DNA supercoiling at
or around H1
B) methylation and phosphorylation of histone
tails
C) hydrolysis of DNA molecules where they are wrapped
around the nucleosome core
D) accessibility of heterochromatin to
phosphorylating enzymes
E) nucleotide excision and
reconstructionB) methylation and phosphorylation of histone tails
b
20) Two potential devices that eukaryotic cells use to regulate
transcription are
A) DNA methylation and histone
amplification.
B) DNA amplification and histone
methylation.
C) DNA acetylation and methylation.
D) DNA
methylation and histone modification.
E) histone amplification
and DNA acetylation.
d
21) During DNA replication,
A) all methylation of the DNA is
lost at the first round of replication.
B) DNA polymerase is
blocked by methyl groups, and methylated regions of the genome
are
therefore left uncopied.
C) methylation of the DNA is
maintained because methylation enzymes act at DNA sites where
one
strand is already methylated and thus correctly methylates daughter
strands after replication.
D) methylation of the DNA is
maintained because DNA polymerase directly
incorporates
methylated nucleotides into the new strand opposite
any methylated nucleotides in the template.
E) methylated DNA is
copied in the cytoplasm, and unmethylated DNA is copied in the nucleus.
c
22) In eukaryotes, general transcription factors
A) are required
for the expression of specific protein-encoding genes.
B) bind to
other proteins or to a sequence element within the promoter called the
TATA box.
C) inhibit RNA polymerase binding to the promoter and
begin transcribing.
D) usually lead to a high level of
transcription even without additional specific
transcription
factors.
E) bind to sequences just after the
start site of transcription.
b
23) Steroid hormones produce their effects in cells by
A)
activating key enzymes in metabolic pathways.
B) activating
translation of certain mRNAs.
C) promoting the degradation of
specific mRNAs.
D) binding to intracellular receptors and
promoting transcription of specific genes.
E) promoting the
formation of looped domains in certain regions of DNA.
d
24) Transcription factors in eukaryotes usually have DNA binding
domains as well as other
domains that are also specific for
binding. In general, which of the following would you expect
many
of them to be able to bind?
A) repressors
B) ATP
C)
protein-based hormones
D) other transcription factors
E) tRNA
d
25) Gene expression might be altered at the level of
post-transcriptional processing in eukaryotes
rather than
prokaryotes because of which of the following?
A) Eukaryotic
mRNAs get 5' caps and 3' tails.
B) Prokaryotic
genes are expressed as mRNA, which is more stable in the cell.
C)
Eukaryotic exons may be spliced in alternative patterns.
D)
Prokaryotes use ribosomes of different structure and size.
E)
Eukaryotic coded polypeptides often require cleaving of signal
sequences before localization.
c
26) Which of the following is most likely to have a small protein
called ubiquitin attached to it?
A) a cyclin that usually acts in
G1, now that the cell is in G2
B) a cell surface protein that
requires transport from the ER
C) an mRNA that is leaving the
nucleus to be translated
D) a regulatory protein that requires
sugar residues to be attached
E) an mRNA produced by an egg cell
that will be retained until after fertilization
A
27) The phenomenon in which RNA molecules in a cell are destroyed if
they have a sequence
complementary to an introduced
double-stranded RNA is called
A) RNA interference.
B) RNA
obstruction.
C) RNA blocking.
D) RNA targeting.
E) RNA disposal.
a
28) At the beginning of this century there was a general announcement
regarding the sequencing
of the human genome and the genomes of
many other multicellular eukaryotes. There was
surprise expressed
by many that the number of protein-coding sequences was much smaller
than
they had expected. Which of the following could account for
most of the rest?
A) "junk" DNA that serves no
possible purpose
B) rRNA and tRNA coding sequences
C) DNA
that is translated directly without being transcribed
D)
non-protein-coding DNA that is transcribed into several kinds of small
RNAs with biological
function
E) non-protein-coding DNA that
is transcribed into several kinds of small RNAs
without
biological function
d
29) Among the newly discovered small noncoding RNAs, one type
reestablishes methylation
patterns during gamete formation and
blocks expression of some transposons. These are known
as
A)
miRNA.
B) piRNA.
C) snRNA.
D) siRNA.
E) RNAi.
b
30) Which of the following best describes siRNA?
A) a short
double-stranded RNA, one of whose strands can complement and
inactivate a
sequence of mRNA
B) a single-stranded RNA that
can, where it has internal complementary base pairs, fold
into
cloverleaf patterns
C) a double-stranded RNA that is
formed by cleavage of hairpin loops in a larger precursor
D) a
portion of rRNA that allows it to bind to several ribosomal proteins
in forming large or
small subunits
E) a molecule, known as
Dicer, that can degrade other mRNA sequences
a
31) One way scientists hope to use the recent knowledge gained about
noncoding RNAs lies with
the possibilities for their use in
medicine. Of the following scenarios for future research,
which
would you expect to gain most from RNAs?
A) exploring
a way to turn on the expression of pseudogenes
B) targeting
siRNAs to disable the expression of an allele associated with
autosomal recessive
disease
C) targeting siRNAs to disable
the expression of an allele associated with autosomal
dominant
disease
D) creating knock-out organisms that can be
useful for pharmaceutical drug design
E) looking for a way to
prevent viral DNA from causing infection in humans
c
32) Since Watson and Crick described DNA in 1953, which of the
following might best explain
why the function of small RNAs is
still being explained?
A) As RNAs have evolved since that time,
they have taken on new functions.
B) Watson and Crick described
DNA but did not predict any function for RNA.
C) The functions of
small RNAs could not be approached until the entire human genome
was
sequenced.
D) Ethical considerations prevented
scientists from exploring this material until recently.
E)
Changes in technology as well as our ability to determine how much of
the DNA is expressed
have now made this possible.
e
33) You are given an experimental problem involving control of a
gene's expression in the
embryo of a particular species.
One of your first questions is whether the gene's expression
is
controlled at the level of transcription or translation. Which
of the following might best give you
an answer?
A) You
explore whether there has been alternative splicing by examining amino
acid sequences
of very similar proteins.
B) You measure the
quantity of the appropriate pre-mRNA in various cell types and find
they are
all the same.
C) You assess the position and
sequence of the promoter and enhancer for this gene.
D) An
analysis of amino acid production by the cell shows you that there is
an increase at this
stage of embryonic life.
E) You use an
antibiotic known to prevent translation.
b
34) In a genome-wide expression study using a DNA microarray assay,
each well is used to
detect the
A) fate of proteins produced
by a cell.
B) location of a protein produced by a cell.
C)
location of a gene within a cell.
D) expression of a specific
gene by a cell.
E) type of chemical modification of proteins
produced by a cell.
d
35) DNA microarrays have had a huge impact on genomic studies because
they
A) can identify the function of any gene in a
genome.
B) can be used to introduce entire genomes into bacterial
cells.
C) allow the expression of many or even all of the genes
in a genome to be compared at once.
D) allow physical maps of the
genome to be assembled in a very short time.
E) dramatically
enhance the efficiency of restriction enzymes (endonucleases).
c
36) Researchers are looking for better treatments for breast cancer.
For a particular DNA
microarray assay (DNA chip), cDNA has been
made from the mRNAs of a dozen patients' breast
tumor
biopsies. The researchers will be looking for a
A) particular
gene that is amplified in all or most of the patient samples.
B)
pattern of fluorescence that indicates which cells are
overproliferating.
C) pattern shared among some or all of the
samples that indicates gene expression differing from
control
samples.
D) group of cDNAs that act differently from those on the
rest of the grid.
E) group of cDNAs that match those in
non-breast-cancer control samples from the same
population.
c
37) Which one of the following techniques involves reverse
transcriptase, PCR amplification,
and gel
electrophoresis?
A) DNA microarray assays
B) RT-PCR
C)
in situ hybridization
D) RNA interference
E) nucleic acid hybridization
b
1) In the microarray shown in Figure 15.1, if you were searching for
genes whose expression was
inhibited by hormone treatment, you
would search for sequences spotted on the array that
showed
________ fluorescence.
A) no
B) high levels of
C)
green
D) red
E) yellow
a
1) If she moves the promoter for the lac operon to the region between
the beta galactosidase
(lacZ) gene and the permease (lacY) gene,
which of the following would be likely?
A) The three structural
genes will be expressed normally.
B) RNA polymerase will no
longer transcribe permease.
C) The operon will no longer be
inducible.
D) Beta galactosidase will not be produced.
E)
The cell will continue to metabolize but more slowly.
d
2) If she moves the operator to the far end of the operon, past the
transacetylase (lacA) gene,
which of the following would likely
occur when the cell is exposed to lactose?
A) The inducer will no
longer bind to the repressor.
B) The repressor will no longer
bind to the operator.
C) The operon will never be
transcribed.
D) The structural genes will be transcribed
continuously.
E) The repressor protein will no longer be produced.
d
3) If she moves the repressor gene (lac I), along with its promoter,
to a position some several
thousand base pairs away from its
normal position, which will you expect to occur?
A) The repressor
will no longer be made.
B) The repressor will no longer bind to
the operator.
C) The repressor will no longer bind to the
inducer.
D) The lac operon will be expressed
continuously.
E) The lac operon will function normally.
e
4) Which of the following is a likely explanation for the lack of
transgene expression in the fifth
cell line?
A) The
transgene integrated into a heterochromatic region of the
genome.
B) The transgene integrated into a euchromatic region of
the genome.
C) The transgene was mutated during the process of
integration into the host cell genome.
D) The host cell lacks the
enzymes necessary to express the transgene.
E) The transgene
integrated into a region of the genome characterized by high histone
acetylation.
a
5) Of the lines that express the transgene, one is transcribed but
not translated. Which of the
following is a likely
explanation?
A) no promoter
B) no AUG in any frame
C)
no compatible ribosome
D) high histone acetylation
E)
missing transcription factor
b
6) In one set of experiments she succeeded in decreasing methylation
of histone tails. Which of
the following results would she most
likely see?
A) increased chromatin condensation
B) decreased
chromatin condensation
C) activation of histone tails for
enzymatic function
D) decreased binding of transcription
factors
E) inactivation of the selected genes
b
7) One of her colleagues suggested she try increased methylation of C nucleotides in a
mammalian system. Which of the following results would she most likely see?
A) increased chromatin condensation
B) decreased chromatin condensation
C) activation of histone tails for enzymatic function
D) decreased binding of transcription factors
E) inactivation of the selected genes
e
8) In one set of experiments using this procedure in Drosophila, she
was readily successful in
increasing phosphorylation of amino
acids adjacent to methylated amino acids in histone tails.
Which
of the following results would she most likely see?
A) increased
chromatin condensation
B) decreased chromatin
condensation
C) activation of histone tails for enzymatic
function
D) decreased binding of transcription factors
E)
inactivation of the selected genes
b
9) In addition, she finds what other evidence of this single-stranded
RNA piece's activity?
A) She can measure the degradation
rate of the remaining single strand.
B) She can measure the
decrease in the concentration of Dicer.
C) The rate of
accumulation of the polypeptide encoded by the target mRNA is
reduced.
D) The amount of miRNA is multiplied by its
replication.
E) The cell's translation ability is
entirely shut down.
c
1) If a particular operon encodes enzymes for making an essential
amino acid and is regulated
like the trp operon, then
A) the
amino acid inactivates the repressor.
B) the enzymes produced are
called inducible enzymes.
C) the repressor is active in the
absence of the amino acid.
D) the amino acid acts as a
corepressor.
E) the amino acid turns on transcription of the operon.
d
2) The functioning of enhancers is an example of
A)
transcriptional control of gene expression.
B) a
post-transcriptional mechanism to regulate mRNA.
C) the
stimulation of translation by initiation factors.
D)
post-translational control that activates certain proteins.
E) a
eukaryotic equivalent of prokaryotic promoter functioning.
a
3) Which of the following is an example of post-transcriptional
control of gene expression?
A) the addition of methyl groups to
cytosine bases of DNA
B) the binding of transcription factors to
a promoter
C) the removal of introns and alternative splicing of
exons
D) the binding of RNA polymerase to transcription
factors
E) the folding of DNA to form heterochromatin
c
4) What would occur if the repressor of an inducible operon were
mutated so it could not bind
the operator?
A) irreversible
binding of the repressor to the promoter
B) reduced transcription
of the operon's genes
C) buildup of a substrate for the
pathway controlled by the operon
D) continuous transcription of
the operon's genes
E) overproduction of catabolite
activator protein (CAP)
d
5) Which of the following statements about the DNA in one of your
brain cells is true?
A) Most of the DNA codes for
protein.
B) The majority of genes are likely to be
transcribed.
C) Each gene lies immediately adjacent to an
enhancer.
D) Many genes are grouped into operon-like
clusters.
E) It is the same as the DNA in one of your kidney cells.
e
6) Which of the following would not be true of cDNA produced using
human brain tissue as the
starting material?
A) It could be
amplified by the polymerase chain reaction.
B) It would contain
sequences representing all the genes in the genome.
C) It was
produced from mRNA using reverse transcriptase.
D) It could be
used as a probe to detect genes expressed in the brain.
E) It
lacks the introns of the human genes.
b