Deck 23: The Regulation of Gene Expression

Question 1

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

Answer 1

C

Question 2

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 LacZ and LacY in the presence of lactose.
D)make LacA in the presence of lactose.
E)make no Lac proteins.

Answer 2

B

Question 3

The situation in which an active regulatory protein "turns off" gene expression is an example of

A)a mutation.
B)positive control.
C)negative control.
D)constitutive gene elements.
E)unique regulation.

Answer 3

C

Question 4

The situation in which an active regulatory protein "turns on" gene expression is an example of

A)feedback inhibition.
B)positive control.
C)negative control.
D)constitutive gene elements.
E)a mutation.

Question 5

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.

Question 6

Effector molecules

A)are associated with the induction of enzyme synthesis.
B)are associated with the repression of enzyme synthesis.
C)induce conformational changes.
D)are often small organic molecules.
E)all of the above

Question 7

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.

Question 8

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

A)XY.
B)XO.
C)XXX.
D)XXY.
E)XXXY.

Question 9

The genetic disorder(s)associated with DNA methylation include

A)Prader-Willi syndrome.
B)Angelman syndrome.
C)some cancers.
D)Huntington's disease.
E)all of the above

Question 10

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.

Question 11

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.

Question 12

A lac 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.

Question 13

The observed "puffs" in the polytene chromosomes of Drosophila are sites of

A)attenuation.
B)condensation.
C)induction.
D)transcription.
E)translation.

Question 14

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

Figure 23.1
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

Question 15

Genes associated with embryonic development are known as

A)homologous genes.
B)sigma factors.
C)heterologous genes.
D)hopanoids.
E)homeotic genes.

Question 16

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 than protein is needed by the cell.
D)RNAs are amplified from a single protein molecule.
E)both choices A and B

Question 17

You are examining an enzyme associated with mannose catabolism.As such,you would expect the protein to be

A)degraded.
B)a hormone.
C)induced by mannose.
D)expressed only during development.
E)expressed only in neurons.

Question 18

Which of the following processes is associated with the altering of histone proteins in vivo?

A)acetylation
B)alkylation
C)methylation
D)transhydroxylation
E)both choices A and C

Question 19

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

Question 20

An E.coli cell with the genotype lac would make which of the following protein products and in what manner?

A)LacZ, induced
B)LacZ and Lac A, induced
C)LacY, constituitive
D)LacZ, constituitive
E)LacZ and LacA, constituitive

Question 21

Regulation of genes between regulatory transcription factors and the RNA polymerase complex is mediated by

A)enhancers.
B)silencers.
C)cofactors.
D)coactivators.
E)sigma factors.

Question 22

Which of the following is not a structural motif associated with transcriptional regulation?

A)combinatorial model
B)helix-turn-helix
C)zinc finger
D)leucine zipper
E)helix-loop-helix

Question 23

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

Question 24

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.

Question 25

Which of the following molecules coordinates the expression of nonadjacent genes?

A)leucine zippers
B)response elements
C)transcription factors
D)coactivators
E)control elements

Question 26

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.

Question 27

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

Question 28

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.

Question 29

One mechanism that may lead to novel disease treatment involves ________,which hinders the translation of specific mRNAs.

A)siRNA
B)iRNA
C)P bodies
D)macro-RNAs
E)rRNA

Question 30

Riboswitches have been observed in

A)prokaryotes.
B)eukaryotes.
C)fungi.
D)algae.
E)yeast.

Question 31

Genes that are expressed only when needed are

A) unregulated.
B)mutations.
C)inducible.
D)constitutive.
E)anabolic.

Question 32

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 choices A and B

Question 33

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

Question 34

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

Question 35

Genes that are always "turned on" in a cell are referred to as

A)regulated genes.
B)mutations.
C)inducible.
D)constitutive.
E)catabolic.

Question 36

The expression of thousands of genes simultaneously is easily accomplished using which of the following techniques?

A)siRNAs
B)Northern blotting
C)microarrays
D)Eastern blotting
E)PAGE analysis

Question 37

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.

Question 38

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

Question 39

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

Question 40

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.

Question 41

________ 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.

Question 42

Multiple operons may be controlled by ________ or ________.

Question 43

A bacteria has the following lac operon genes located on the chromosome: I⁺P⁻Z⁻Y⁻A⁺.On a plasmid,this same bacterial cell has the lac genes I⁻P⁺Z⁻Y⁺A⁻.Which Lac proteins will be made? What type of protein expression (induced or constituitive)will there be for each protein that is made ?

Question 44

Discuss how DNA methylation is associated with genomic imprinting.Be sure to use examples.

Question 45

Groups of operons that are regulated by the same regulatory protein are known as ________.

Question 46

What is therapeutic cloning,and what are some of the ethical considerations for its use?

Question 47

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.

Question 48

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

Question 49

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

Question 50

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

Question 51

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

Question 52

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

Question 53

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 ________.

Question 54

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

Question 55

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

Question 56

How can you determine the type of regulatory control associated with a newly identified bacterial protein?

Question 57

What is the difference between trans- and cis-acting regulatory factors? Design an experiment that allows you to prove your answer to the question.

Question 58

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