Deck 11: Gene Regulation

Question 1

A(n)________ operon is one whose transcription is decreased by effector molecules.

A)activated
B)repressible
C)inducible
D)coinducible
E)compressible

Answer 1

B

Question 2

A bacteria contains two copies of the lac operon;one on the bacterial chromosome and one on a plasmid.The lacO site on the chromosomal lac operon is mutated and non-functional whereas the lacO site on the plasmid is functional.What is the most likely outcome for the bacterial cell when lactose is not available?

A)Expression of lac structural genes on the chromosome and plasmid will decrease because two copies of the lacO site are needed for repression of the lac operon.
B)Expression of lac structural genes on the plasmid,but not the chromosome,will increase because the mutation in the chromosomal lacO gene will prevent the expression of the genes.
C)Expression of lac structural genes on the chromosome but not the plasmid will increase because repressor proteins are unable to bind to the chromosomal lacO site,but are capable of binding the plasmid lacO site.
D)Expression of lac structural genes will not change because the lacO site is not a structural gene.

Answer 2

C

Question 3

The lacA gene found within the lac operon encodes for galactosidase transacetylase.This enzyme attaches a(n)________ group to lactose and lactose analogs.

A)amino
B)hydroxyl
C)carbonyl
D)acetyl
E)carboxyl

Answer 3

D

Question 4

When the lac repressor binds to the lac operator site,RNA polymerase is prevented from transcribing which genes?

A)the galactosidase gene
B)a regulatory gene
C)the galactoside transacetylase gene
D)the galactosidase and galactoside transacetylase genes
E)the galactosidase gene and a regulatory gene

Question 5

Genes organized into an operon are beneficial to certain bacteria because the operon allows for

A)discrete regulation of each gene encoding proteins with common functions.
B)coordinated regulation of a group of genes that encode proteins in a common pathway.
C)discrete regulation of each gene that encodes proteins with different functions.
D)coordinated regulation of a group of genes that encode proteins used in different pathways.
E)coordinated regulation of all the proteins within the genomE.

Question 6

Liver cells,mammary cells,and skin cells all contain the same genome;however,their respective proteomes vary drastically.This observation is best explained by what phenomenon?

A)gene splicing
B)cell division
C)cell differentiation
D)crossing over
E)evolution

Question 7

Small effector molecules

A)are always present in the cytoplasm.
B)are only found in the nucleus of the cell.
C)regulate gene transcription by binding to DNA.
D)regulate gene transcription by binding a regulatory protein.

Question 8

What happens when the cAMP-CAP complex binds the CAP site near the lac promoter?

A)Transcription rate decreases.
B)Transcription rate increases.
C)RNA polymerase binds to the promoter.
D)RNA polymerase binds to the promoter and transcription rate decreases.
E)RNA polymerase binds to the promoter and transcription rate increases.

Question 9

An mRNA that contains the coding sequence for two or more structural genes is called a

A)polyintronic mRNA.
B)polyextronic mRNA.
C)polycistronic mRNA.
D)polyexpressive mRNA.
E)polyrepressor mRNA.

Question 10

The lacP site within the lac operon is upstream of the genes that encode for lactose uptake and metabolism proteins.The lacP site is

A)the lac promoter site.
B)where RNA polymerase binds.
C)the site where genes are transcribed that encode proteins for metabolizing lactose.
D)the lac promoter site where RNA polymerase binds.
E)the lac promoter site,where genes are transcribed that encode proteins for metabolizing lactosE.

Question 11

What type of regulatory transcription factor binds DNA in order to increases the transcription of a gene?

A)a repressor exerting negative control
B)a repressor exerting positive control
C)an activator exerting negative control
D)an activator exerting positive control
E)a combination of both a repressor and activator exerting negative control

Question 12

The molecule that functions as a corepressor for the trp operon is

A)glucose.
B)cAMP.
C)tryptophan.
D)CAP.
E)lactosE.

Question 13

A mutation in the CAP protein occurs such that it permanently binds cAMP.What is the likely effect on lac operon gene expression when glucose concentration is high and lactose is present?

A)Lac operon gene expression will decrease until glucose concentrations drop.
B)Lac operon gene expression will increase until glucose concentrations drop.
C)Lac operon gene expression will permanently glucose,regardless of lactose concentration.
D)Lac operon gene expression will permanently increase,regardless of glucose concentration.

Question 14

The major difference in gene regulation between prokaryotes and eukaryotes is

A)eukaryotic and prokaryotic genes are usually grouped for common functions.
B)eukaryotic genes regulation requires fewer signals than prokaryotic gene regulation.
C)eukaryotic gene regulation is more simplistic than prokaryotic gene regulation.
D)eukaryotic genes are arranged individually,while prokaryotic genes are grouped into operons.
E)eukaryotic gene regulation tends to require less coordination and integration than prokaryotic gene regulation.

Question 15

Genes expressed at relatively constant levels in tissues regardless of variations in the animal's condition are called a

A)transposable element.
B)steady state gene.
C)constitutive gene.
D)recombinant gene.
E)multifunctional genE.

Question 16

A cell's ability to control their level of gene expression is called

A)gene transformation.
B)gene regulation.
C)gene splicing.
D)gene addition.
E)gene correction.

Question 17

The ability of glucose to repress the lac operon depends on which effector molecules?

A)allolactose
B)cAMP
C)tryptophan
D)ADP
E)starch

Question 18

What would be the most likely outcome for a cell if a gene expressed at relatively constant but low levels were mutated to dynamically respond to environmental changes?

A)The cell could experience an ideal balance of proteins that might affect cellular function.
B)The cell would not be affected because no protein changes would occur.
C)The cell would experience increased function because having more of a protein is always an improvement.
D)The cell would likely have more and less protein at different times that would affect cellular function.

Question 19

What is the likely outcome from a mutation in the lacO site (lac operator)of the lac operon?

A)Binding of RNA polymerase could be hindered,so transcription would be repressed.
B)Binding of a repressor protein could be hindered,so transcription would be active.
C)Binding of the activator protein could be hindered,so transcription would be repressed.
D)Binding of the sigma factor to RNA Polymerase would be hindered,so transcription would be represseD.
E)The order in which the genes of the lac operon are transcribed would be altered.

Question 20

A eukaryotic gene that is regulated by three activator proteins is said to be under

A)triplet regulation.
B)individual control.
C)self-regulation.
D)combinatorial control.
E)elastic control.

Question 21

Eukaryotic DNA methylation occurs on which base?

A)guanine
B)cytosine
C)thymine
D)adenine
E)thymine and adenine

Question 22

When lactose becomes available the genes encoding b-galactosidase and lactose permease are upregulated in
E.coli.

Question 23

Bacteria can regulate gene expression by controlling the rate at which mRNA is translated into protein.

Question 24

Why would bacteria evolve so that the presence of tryptophan inhibits its own production?

A)Producing the enzymes that synthesize tryptophan is metabolically expensive,so it is wasteful to make them when tryptophan levels are high and its synthesis is not necessary.
B)Producing high levels of tryptophan inhibits the production of other amino acids,so inhibiting its production allows all amino acids to be synthesized at equal concentrations.
C)High levels of tryptophan causes cells to become unresponsive to external stimuli,so its production must be regulated.
D)High levels of tryptophan inhibit cellular respiration and the synthesis of ATP,so its production must be regulateD.
E)All of these choices are TRUE.

Question 25

Loosely packed chromatin is said to be in an open conformation.

Question 26

MicroRNAs (miRNAs)

A)are long RNA molecules.
B)silence the expression of specific mRNAs.
C)silence the expression of any mRNA present in the cytoplasm.
D)are cut by an enzyme called transcriptase.
E)are found only in animals.

Question 27

DNA methylation

A)increases transcription.
B)inhibits transcription.
C)increases crossover events.
D)decreases crossover events.
E)promotes post-translational modification of proteins.

Question 28

MicroRNAs increase the rate of mRNA translation.

Question 29

Both eukaryotes and prokaryotes require a promoter region for gene transcription.

Question 30

An activator is to an enhancer as a(n)_____ is to a silencer.

A)transcription factor
B)inducer
C)repressor
D)mediator
E)RNA polymerase II

Question 31

Different globin polypeptides are expressed at similar levels during the embryonic and fetal stages of mammalian development.

Question 32

Unmethylated CpG islands are correlated with inactive genes.

Question 33

What could be a possible consequence if a structural gene's TATA box is mutated?

A)The transcriptional start site may not function properly.
B)Transcription may start at a variety of sites.
C)Unusable transcripts may be produced.
D)The preinitiation complex may form at the wrong site.
E)All of the choices are correct.

Question 34

The core promoter in eukaryotes is usually composed of which two features?

A)transcriptional start site and enhancer
B)transcriptional start site and response elements
C)transcriptional start site and TATA box
D)enhancer and TATA box
E)response elements and TATA box

Question 35

A scientist uses recombinant technology to take a eukaryotic promoter and place it in front of a bacterial structural gene.What is the most likely outcome on bacterial gene expression?

A)Bacterial gene expression will increase because both prokaryotic and eukaryotic genes are based on the same four nucleotides.
B)Bacterial gene expression will not occur because RNA polymerase enzymes between prokaryotes and eukaryotes are incompatible.
C)Bacterial gene expression will increase because eukaryotic RNA polymerase has analogous function to prokaryotic RNA polymerase.
D)Bacterial gene expression will decrease slightly because prokaryotic RNA polymerase cannot transcribe eukaryotic genes as efficiently as prokaryotic genes.

Question 36

Eukaryotic genes are almost always organized in groups,similar to operons in prokaryotes.

Question 37

Events that occur during transcriptional regulation in eukaryotes include

A)DNA replication.
B)mRNA translation.
C)RNA processing and export from the nucleus.
D)polypeptide synthesis.
E)all of thesE.

Question 38

The general transcription factor TFIID

A)recognizes the enhancer.
B)recognizes the TATA box.
C)recognizes the silencer.
D)transcribes mRNA.
E)is a silencer.

Question 39

When cytosolic levels of iron increase,intracellular ferritin levels will

A)decrease.
B)not change.
C)increase.
D)fluctuate by increasing and decreasing in a random fashion.
E)drop until iron levels increase further.

Question 40

Small effector molecules directly bind the DNA they regulate.

Question 41

Histone deacetylase inhibitors are a class of drugs used as mood stabilizers and anti-epileptics that are also being researched for their efficacy as anti-cancer agents.Histone deacetylase inhibitors block the action of histone deacetylases,which remove acetyl groups from lysine residues in histone tails.How will blocking histone deacetylases affect gene expression in the cell?

A)Chromatin will become more tightly compact,and gene expression will be reduced
B)Chromatin will become more tightly compact,and gene expression will be increased
C)Chromatin will become more open,and gene expression will be reduced
D)Chromatin will become more open,and gene expression will be increased
E)Chromatin will become more methylated,and gene expression will be decreased

Question 42

Certain drugs use RNA interference as a mechanism of action.What molecule would the active compounds of these drugs be composed of?

A)Carbohydrate
B)Steroid
C)Protein
D)Nucleic acid
E)Small ion

Question 43

A gene that has 3 exons A,B and C and 2 introns undergoes alternative splicing.What is the mRNA pool that would result from gene expression of this region?

A)A-B and B-C
B)A,B,and C
C)A-B-C
D)A-C
E)All of these would be found in the pool.