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45 Cards in this Set

  • Front
  • Back
In eukaryotes, gene amplification is tolerated well when the amplified gene encodes for RNA products. However, it is rare or detrimental when the product is a protein. Why would it be advantageous for the cell to amplify the RNA-producing genes and not the protein-producing ones?
A)

It allows for the manufacture of many RNA molecules when needed in the cell.
B)

Proteins are amplified from a single mRNA molecule.
C)

More RNA is needed by the cell than protein.
D)

RNAs are amplified from a single protein molecule.
E)

both A and B
A)

It allows for the manufacture of many RNA molecules when needed in the cell.
B)

Proteins are amplified from a single mRNA molecule.
You are examining an enzyme associated with glycolysis. As such, you would expect
A)

the protein to be a hormone.
B)

the protein to be induced by glucose.
C)

the protein to be constitutively expressed.
D)

the protein to be expressed only during development.
E)

the protein to be expressed only during mitosis.
C)

the protein to be constitutively expressed.
A lac Y– mutant would
A)

be constitutive.
B)

no longer be induced by the presence of lactose.
C)

not have β galatosidase activity.
D)

transport lactose into the cell effectively.
E)

metabolize lactose.
D)

transport lactose into the cell effectively.
An E.coli cell with the genotype lac OcZ+Y–A– would make which of the following protein products and in what manner?
A)

Lac Z, induced
B)

Lac Z and Lac A, induced
C)

Lac Y, constituitive
D)

Lac Z, constituitive
E)

Lac Z and Lac A, constituitive
D)

Lac Z, constituitive
The main chromosome of a bacterial cell possesses the following genotype with regard to the Lac operon:
I–O+Z+Y–A–. This bacterial cell would
A)

make LacZ in the presence of lactose.
B)

make LacZ independently of lactose.
C)

make Lac Z and Lac Y in the presence of lactose.
D)

make LacA in the presence of lactose.
E)

make no lac proteins.
B)

make LacZ independently of lactose.
Genes associated with embryonic development are known as
A)

homologous genes.
B)

sigma factors.
C)

heterologous genes.
D)

hopanoids.
E)

homeotic genes.
E)

homeotic genes.
The observed "puffs" in the polytene chromosomes of Drosophila are sites of
A)

attenuation.
B)

condensation.
C)

induction.
D)

transcription.
E)

translation.
D)

transcription.
The situation in which an active regulatory protein "turns on" expression is an example of
A)

feedback inhibition.
B)

positive control.
C)

negative control.
D)

constitutive gene elements.
E)

a mutation.
B)

positive control.
The situation in which an active regulatory protein "turns off" expression is an example of
A)

a mutation.
B)

positive control.
C)

negative control.
D)

constitutive gene elements.
E)

unique regulation.
C)

negative control.
The graph below shows a growth curve of E. coli growing in a defined medium containing equal molar amounts of glucose and lactose.



Based on your knowledge of the regulation of the lac operon, the best explanation of these results is that
A)

early on, due to the presence of lactose, the bacteria utilize the lac operon. Glucose is used later.
B)

the bacteria are utilizing both sugars simultaneously.
C)

the presence of glucose causes the formation of cAMP catabolic repressor protein (CRP) complexes, which shut down the lac operon until the glucose is used up.
D)

glucose is used first. Once glucose becomes limiting, intracellular cAMP increases, forming cAMP-CRP complexes that activate the lac operon to use lactose.
E)

none of the above
D)

glucose is used first. Once glucose becomes limiting, intracellular cAMP increases, forming cAMP-CRP complexes that activate the lac operon to use lactose.
Effector molecules
A)

are associated with induction of enzyme synthesis.
B)

are associated with repression of enzyme synthesis.
C)

induce conformational changes.
D)

are often small organic molecules.
E)

all of the above
E)

all of the above
The trp operon in E. coli is regulated in such a manner as to allow expression of the genes only when cellular levels of tryptophan are low. When tryptophan levels are adequate, the secondary structure of the mRNA halts translation. This form of regulation is known as
A)

attenuation.
B)

transcriptional regulation.
C)

positive regulatory control.
D)

negative regulatory control.
E)

repression.
A)

attenuation.
Which of the following is an example of translational regulation?
A)

protein degradation
B)

DNA splicing
C)

protein folding
D)

mRNA degradation
E)

DNA methylation
D)

mRNA degradation
A person with the genotype XXXY would be expected to have how many Barr bodies?
A)

0
B)

1
C)

2
D)

3
E)

4
C)

2
A male is tested for cellular abnormalities. Within each of his cells, the technician notes that there are two Barr bodies present within his cells. As a result he has the genotype
A)

XY.
B)

XO.
C)

XXX.
D)

XXY.
E)

XXXY.
E)

XXXY.
A lacOc mutant would
A)

never make lac structural genes.
B)

be constitutively expressed.
C)

bind receptor protein.
D)

have repressed expression.
E)

be able to be induced by lactose.
B)

be constitutively expressed.
Sigma (σ) factors can regulate the initiation of transcription. Which of the following is NOT an example of σ regulation?
A)

Some σ factors recognize promoters for genes whose products are necessary when the organism is under stress, such as heat shock.
B)

Some σ factors recognize genes necessary for nitrogen utilization.
C)

Bacteriophages may code for specific σ factors that bind the core RNA polymerase and result in recognition of viral promoters.
D)

There are many σ sigma factors associated with eukaryotic organisms.
D)

There are many σ sigma factors associated with eukaryotic organisms.
Genes that are always "turned on" in a cell are referred to as
A)

regulated genes.
B)

mutations.
C)

inducible.
D)

constitutive.
E)

catabolic.
D)

constitutive.
Of the enzymes associated with the metabolism of lactose with the lac operon, the one associated with transport of lactose into the cell is
A)

β galactosidase.
B)

transacetylase.
C)

galactoside permease.
D)

β lactase.
E)

lactose translocase.
C)

galactoside permease.
You are working with a gene associated with an essential pathway that is necessary at two time points in an organism's lifetime. With regard to gene regulation, you would expect the gene to be
A)

not constitutive.
B)

associated with response to distinct events.
C)

"activated" by particular signals (induced).
D)

"turned off" by particular signals (repressed).
E)

all of the above
E)

all of the above
A certain gene is transformed into a plant cell for potential use as a vaccine delivery system. Upon performing a Northern blot, a good deal of mRNA for the gene is produced. However, the protein product for the gene is not observed. One explanation may be that the
A)

plant cell recognizes and degrades the protein in the cytoplasm.
B)

plant ribosomes are not recognizing the mRNA translational initiation sites.
C)

mRNA is not stable in the plant cytoplasm.
D)

all of the above
E)

none of the above
D)

all of the above
Which of the following does NOT apply to eukaryotic gene regulation?
A)

gene regulation by attenuation
B)

regulation as a result of compartmentalization
C)

mRNA degradation (turnover)
D)

protein degradation (turnover)
E)

protein folding
A)

gene regulation by attenuation
You are studying a biochemical pathway. Preliminary results suggest that this pathway is subject to end-product repression. This pathway is therefore most likely to be a(n) ________ pathway.
A)

anabolic
B)

catabolic
C)

constitutive
D)

induced
E)

unregulated
A)

anabolic
A transcriptional regulator that decreases transcription of a gene from a vast distance is known as a(n)
A)

enhancer.
B)

upstream control element.
C)

regulator.
D)

nonsense mutation.
E)

silencer.
E)

silencer.
Within a genome, an enhancer may be located
A)

upstream of the gene enhanced.
B)

downstream of the gene enhanced.
C)

within the gene enhanced.
D)

choices A, B, and C
E)

both A and B
E)

both A and B
The lac repressor is
A)

active when glucose is present.
B)

inactive when glucose is present.
C)

active when both glucose and lactose are present.
D)

induced when cAMP is present.
E)

rarely active.
A)

active when glucose is present.
In the lac operon, Is mutations allow
A)

constitutive expression of Lac proteins.
B)

regulated expression of Lac proteins.
C)

β-galactosidase activity, only.
D)

no expression of Lac proteins.
E)

none of the above
D)

no expression of Lac proteins.
Small molecules that bind directly to mRNAs and effect transcription or translation are binding to regions of the mRNA known as
A)

Shine-Delgarno sequences.
B)

the operator region.
C)

riboswitches.
D)

ribozymes.
E)

allosteric sites.
C)

riboswitches.
Riboswitches have been observed in
A)

prokaryotes.
B)

eukaryotes.
C)

fungi.
D)

algae.
E)

yeast.
A)

prokaryotes.
DNA rearrangements in vertebrates occur in the
A)

glycolysis genes.
B)

cell surface protein genes.
C)

viral protein genes.
D)

antibody genes.
E)

none of the above
D)

antibody genes.
The degradation of mRNA in the cells occurs in clusters known as
A)

iRNA sites.
B)

sRNA regions.
C)

nuceoli.
D)

P bodies.
E)

N sites.
D)

P bodies.
One mechanism that may lead to novel disease treatment is ________, which hinders the translation of specific mRNAs.
A)

siRNA
B)

iRNA
C)

P bodies
D)

macro-RNAs
E)

rRNA
A)

siRNA
In the lactose operon, a P mutant would have a mutation in the ________ region of the operon.
Answer:

promoter
Although Dolly the cloned sheep and her nucleus donor are clones, they do not contain the same ________ DNA.
Answer:

mitochondrial
________ is the term given to the process by which cells delete genes when the gene products are no longer required, as occurs in mammalian red blood cells.
Answer:

Gene deletion or gene diminution
The nucleus of a differentiated cell contains all of the genetic information necessary to direct the development of an entire organism. This nucleus is therefore said to be ________.
Answer:

totipotent
In order to activate genes associated with sugar metabolism, the levels of cAMP are ________ in a bacterial cell.
Answer:

high
Regions of the genome that are inactive often have ________ of C nucleotides.
Answer:

methylation
Changes in gene expression that are not the result of changes to the gene itself are known as ________ changes.
Answer:

epigenetic
Inactivated X chromsomes form dark spots in the nucleus known as ________.
Answer:

Barr bodies
An individual that is XXY has ________ Barr body(ies) in their cells.
Answer:

1
Transcriptionally active chromatin has a large content of ________ proteins, nonhistone proteins associated with chromatin.
Answer:

high-mobility group (HMG)
Groups of operons that are regulated by the same regulatory protein are known as ________.
Answer:

regulons
Multiple operons may be controlled by ________ or ________.
Answer:

regulons, stimulons
The ________ experiments use an initial exposure to a radioactive compound in the mRNA followed by monitoring of the radioactive compound to determine its fate in the cell.
Answer:

pulse-charge