Question 1

Compare and contrast AraC with trans-factors that regulate the lac operon.

Accepted Answer

AraC,LacI,and CRP are all trans-factors,and all are regulated by metabolites (arabinose,lactose,and cAMP,respectively).However,AraC is a positive regulator of araBAD,whereas LacI is a negative regulator of lacZYA,meaning that in the presence of arabinose,AraC binds to DNA near the promoter and facilitates transcription,whereas when LacI binds near its promoter,it inhibits transcription.CRP,like AraC binds to DNA to facilitate transcription,and does so only when it is bound to its metabolic regulator.However,CRP is ultimately regulated (negatively)by glucose levels-so high glucose limits the activity of CRP,whereas high arabinose increases the activity of AraC.

Question 2

Proteins that undergo reversible changes in conformation when bound to another molecule are called ________________.

Accepted Answer

A)  reverse proteins 
B)  allosteric proteins 
C)  regulatory proteins 
D)  activator proteins 
E)  allostatic proteins 
A)  reverse proteins 
B)  allosteric proteins 
C)  regulatory proteins 
D)  activator proteins 
E)  allostatic proteins B

Question 3

Global regulatory control of gene expression in bacteria can be achieved by the binding of alternate sigma (σ)factors to RNA polymerase.

Accepted Answer

A) True 
 B)False  True

Question 4

What term describes a second level of regulation of the trp operon that occurs in TrpR- mutants suggesting that it is repressor independent?

Accepted Answer

A)  modulation 
B)  derepression 
C)  attenuation 
D)  amplification 
E)  desensitization 
A)  modulation 
B)  derepression 
C)  attenuation 
D)  amplification 
E)  desensitization

Question 5

How do negative regulators such as the lac repressor prevent RNA polymerase from initiating transcription?

Accepted Answer

A)  by blocking passage of the polymerase through the operator 
B)  by forming a loop in the operator that restricts the passage of the polymerase 
C)  by physically blocking the DNA binding site of RNA polymerase 
D)  by binding to the polymerase,thus preventing its binding 
E)  by degrading metabolic activators 
A)  by blocking passage of the polymerase through the operator 
B)  by forming a loop in the operator that restricts the passage of the polymerase 
C)  by physically blocking the DNA binding site of RNA polymerase 
D)  by binding to the polymerase,thus preventing its binding 
E)  by degrading metabolic activators

Question 6

Which of the following does not act in cis?

Accepted Answer

A)  lacO 
B)  attenuation 
C)  lacOc 
D)  trpR 
E)  araI 
A)  lacO 
B)  attenuation 
C)  lacOc 
D)  trpR 
E)  araI

Question 7

Explain how three enzymes appear simultaneously when lactose is introduced into a bacterial culture medium as the sole carbon source.

Accepted Answer

The three enzymes are translat

Question 8

Which of the following combinations will produce the highest expression of ?-galactosidase? Assume crp- is a complete deletion of CRP (cAMP receptor protein).

Accepted Answer

A)  lacI+,crp- on medium with glucose but no lactose 
B)  lacIs,crp- on medium with lactose but no glucose 
C)  lacI+,crp- on medium with both glucose and lactose 
D)  lacOc,crp+ on medium with glucose but no lactose 
E)  lacOc,crp+,on medium with both glucose and lactose 
A)  lacI+,crp- on medium with glucose but no lactose 
B)  lacIs,crp- on medium with lactose but no glucose 
C)  lacI+,crp- on medium with both glucose and lactose 
D)  lacOc,crp+ on medium with glucose but no lactose 
E)  lacOc,crp+,on medium with both glucose and lactose

Question 9

Distinguish between positive and negative regulation of transcription.

Accepted Answer

Negative regulation involves the inhibit

Question 10

Describe the two binding domains on the lac repressor protein.

Accepted Answer

The repressor has tw

Question 11

Initiation of transcription by RNA polymerase involves the binding of which of the following subunits to the core enzyme?

Accepted Answer

A)  delta 
B)  sigma 
C)  gamma 
D)  alpha 
E)  zeta 
A)  delta 
B)  sigma 
C)  gamma 
D)  alpha 
E)  zeta

Question 12

In prokaryotes,the gene regulation primarily occurs by either blocking or enhancing transcription.

Accepted Answer

A) True 
 B)False

Question 13

Compare and contrast the trans-factors that regulate the lac and trp operons.

Accepted Answer

Both lac and trp operons are regulated b

Question 14

How does tryptophan,the end product of the trp operon,function in the regulation of the operon?

Accepted Answer

A)  It binds to the repressor preventing it from binding to DNA thus allowing transcription of the operon. 
B)  It binds to the repressor and only then can the repressor bind to DNA allowing transcription of the operon. 
C)  It binds directly to RNA and inhibits translation of the operon. 
D)  It binds to the repressor and only then can this complex bind to DNA preventing transcription of the operon. 
E)  It binds directly to DNA and inhibits transcription of the operon. 
A)  It binds to the repressor preventing it from binding to DNA thus allowing transcription of the operon. 
B)  It binds to the repressor and only then can the repressor bind to DNA allowing transcription of the operon. 
C)  It binds directly to RNA and inhibits translation of the operon. 
D)  It binds to the repressor and only then can this complex bind to DNA preventing transcription of the operon. 
E)  It binds directly to DNA and inhibits transcription of the operon.

Question 15

Positive regulators actually physically bind to RNA polymerase and enhance the enzyme's ability to initiate transcription.

Accepted Answer

A) True 
 B)False

Question 16

A common DNA structural feature involved in gene regulatory systems is

Accepted Answer

A)  supercoiling of DNA. 
B)  looping of the DNA. 
C)  unwinding of the double helix. 
D)  coiling into Z-DNA. 
E)  plasmid formation. 
A)  supercoiling of DNA. 
B)  looping of the DNA. 
C)  unwinding of the double helix. 
D)  coiling into Z-DNA. 
E)  plasmid formation.

Question 17

More than 20 different DNA-binding proteins in bacteria are similar to the LacI repressor,creating the LacI repressor family of proteins.Why do they all not bind at the lac operator and repress the lac operon?

Accepted Answer

Each of the LacI repressor pro

Question 18

How are complex processes such as sporulation,synthesis of flagella,and nitrogen fixation that require the transcription of multiple sets of genes regulated in bacteria?

Accepted Answer

A)  Multiple operons are simultaneously induced. 
B)  A hormone activates transcription of each gene simultaneously. 
C)  The end product of one operon is used as an inducer of the next operon in sequence. 
D)  There are single operons consisting of many genes for each of these processes. 
E)  Cascades of sigma factors synthesized in a temporal order,allow the turning on of successive sets of genes. 
A)  Multiple operons are simultaneously induced. 
B)  A hormone activates transcription of each gene simultaneously. 
C)  The end product of one operon is used as an inducer of the next operon in sequence. 
D)  There are single operons consisting of many genes for each of these processes. 
E)  Cascades of sigma factors synthesized in a temporal order,allow the turning on of successive sets of genes.

Question 19

What would be the phenotype of a mutation that altered lac repressor function?

Accepted Answer

A)  constitutive 
B)  inducible 
C)  permanently repressed 
D)  auxotrophic 
E)  allotrophic 
A)  constitutive 
B)  inducible 
C)  permanently repressed 
D)  auxotrophic 
E)  allotrophic

Question 20

In the example of the lac operon,and most operons,what is the significance of a polycistronic message?

Accepted Answer

A polycistronic mess

Exam 9: Genome Annotation

Compare and contrast AraC with trans-factors that regulate the lac operon.

Proteins that undergo reversible changes in conformation when bound to another molecule are called ________________.

Global regulatory control of gene expression in bacteria can be achieved by the binding of alternate sigma (σ)factors to RNA polymerase.

What term describes a second level of regulation of the trp operon that occurs in TrpR- mutants suggesting that it is repressor independent?

How do negative regulators such as the lac repressor prevent RNA polymerase from initiating transcription?

Which of the following does not act in cis?

Explain how three enzymes appear simultaneously when lactose is introduced into a bacterial culture medium as the sole carbon source.

Which of the following combinations will produce the highest expression of ?-galactosidase? Assume crp- is a complete deletion of CRP (cAMP receptor protein).

Distinguish between positive and negative regulation of transcription.

Describe the two binding domains on the lac repressor protein.

Initiation of transcription by RNA polymerase involves the binding of which of the following subunits to the core enzyme?

In prokaryotes,the gene regulation primarily occurs by either blocking or enhancing transcription.

Compare and contrast the trans-factors that regulate the lac and trp operons.

How does tryptophan,the end product of the trp operon,function in the regulation of the operon?

Positive regulators actually physically bind to RNA polymerase and enhance the enzyme's ability to initiate transcription.

A common DNA structural feature involved in gene regulatory systems is

More than 20 different DNA-binding proteins in bacteria are similar to the LacI repressor,creating the LacI repressor family of proteins.Why do they all not bind at the lac operator and repress the lac operon?

How are complex processes such as sporulation,synthesis of flagella,and nitrogen fixation that require the transcription of multiple sets of genes regulated in bacteria?

What would be the phenotype of a mutation that altered lac repressor function?

In the example of the lac operon,and most operons,what is the significance of a polycistronic message?

Mendels Principles of Heredity

Extensions to Mendels Laws

The Chromosome Theory of Inheritance

Linkage, Recombination, and the Mapping of Genes on Chromosomes

Dna Structure, Replication, and Recombination

Anatomy and Function of a Gene: Dissection Through Mutation

Gene Expression: the Flow of Information From Dna to Rna to Protein

Digital Analysis of Genomes

Analyzing Genomic Variation

The Eukaryotic Chromosome

Chromosomal Rearrangements and Changes in Chromosome Number

Bacterial Genetics

Organellar Inheritance

Gene Regulation in Prokaryotes

Gene Regulation in Eukaryotes

Manipulating the Genomes of Eukaryotes

The Genetic Analysis of Development

The Genetics of Cancer

Variation and Selection in Populations

Genetics of Complex Traits

Exploring Synthetic Biology: Concepts, Techniques, and Applications

Filters

What term describes a second level of regulation of the trp operon that occurs in TrpR^- mutants suggesting that it is repressor independent?

Which of the following combinations will produce the highest expression of ?-galactosidase? Assume crp^- is a complete deletion of CRP (cAMP receptor protein).