Question 1

You are examining an enzyme associated with cysteine biosynthesis.You would expect expression of the enzyme to be

Accepted Answer

A) amplified when cysteine concentrations are high. 
B) induced by cysteine. 
C) repressed by cysteine. 
D) high when ATP concentrations in the cell are low. 
E) controlled by a riboswitch. 
A) amplified when cysteine concentrations are high. 
B) induced by cysteine. 
C) repressed by cysteine. 
D) high when ATP concentrations in the cell are low. 
E) controlled by a riboswitch. C

Question 2

The accompanying graph 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

Accepted Answer

A) early on,due to the presence of lactose,the bacteria use the lac operon.Glucose is used later. 
B) the bacteria use 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) early on the glucose binds to the repressor protein lacI and shuts down the lac operon. 
A) early on,due to the presence of lactose,the bacteria use the lac operon.Glucose is used later. 
B) the bacteria use 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) early on the glucose binds to the repressor protein lacI and shuts down the lac operon. D

Question 3

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

Accepted Answer

Trans-acting factors can regulate product regardless of where the gene is located within the genome.On the other hand,cis-acting factors need to be adjacent to the region being regulated in order to exert their effects.The designed experiments should support these findings.The lac operon provides excellent examples of support.

Question 4

The chromosome of a bacterial cell possesses the following genotype with regard to the lac operon: I−O+Z+Y−A−.This bacterial cell would

Accepted Answer

A) make β-galactosidase in the presence of lactose. 
B) make β-galactosidase independently of lactose. 
C) make β-galactosidase and galactoside permease in the presence of lactose. 
D) make transacetylase in the presence of lactose. 
E) make no lac gene products. 
A) make β-galactosidase in the presence of lactose. 
B) make β-galactosidase independently of lactose. 
C) make β-galactosidase and galactoside permease in the presence of lactose. 
D) make transacetylase in the presence of lactose. 
E) make no lac gene products.

Question 5

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 ________.

Accepted Answer

The answer of The nucleus of a differentiated cell contains...

Question 6

Within a genome,an enhancer may be located

Accepted Answer

A) upstream of the gene enhanced. 
B) downstream of the gene enhanced. 
C) within the introns of other genes. 
D) proximal to the gene enhanced. 
E) upstream or downstream of the gene enhanced,even within the introns of other genes. 
A) upstream of the gene enhanced. 
B) downstream of the gene enhanced. 
C) within the introns of other genes. 
D) proximal to the gene enhanced. 
E) upstream or downstream of the gene enhanced,even within the introns of other genes.

Question 7

A lac I− mutant would

Accepted Answer

A) express lacZYA constitutively. 
B) not induce lacZYA in the presence of lactose. 
C) not have β-galactosidase activity. 
D) not transport lactose into the cell effectively. 
E) not metabolize lactose. 
A) express lacZYA constitutively. 
B) not induce lacZYA in the presence of lactose. 
C) not have β-galactosidase activity. 
D) not transport lactose into the cell effectively. 
E) not metabolize lactose.

Question 8

Effector molecules

Accepted Answer

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 these are true. 
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 these are true.

Question 9

In eukaryotes,gene amplification is ________ and may occur when ________.

Accepted Answer

A) the creation of multiple copies of the same gene; a large amount of the gene product is required for cell function 
B) a sudden increase in transcription of a gene; a large amount of the gene product is required for cell function 
C) a sudden increase in translation of a mRNA; a large amount of the gene product is required for cell function 
D) the creation of multiple copies of the same gene; transcription and translation are suppressed 
E) a sudden increase in transcription of a gene; translation is suppressed 
A) the creation of multiple copies of the same gene; a large amount of the gene product is required for cell function 
B) a sudden increase in transcription of a gene; a large amount of the gene product is required for cell function 
C) a sudden increase in translation of a mRNA; a large amount of the gene product is required for cell function 
D) the creation of multiple copies of the same gene; transcription and translation are suppressed 
E) a sudden increase in transcription of a gene; translation is suppressed

Question 10

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.

Accepted Answer

A) anabolic 
B) catabolic 
C) constitutive 
D) induced 
E) unregulated 
A) anabolic 
B) catabolic 
C) constitutive 
D) induced 
E) unregulated

Question 11

Cloning eukaryotic organisms involves the transfer of a ________ into a cell that lacks one to direct the development of a new organism.

Accepted Answer

The answer of Cloning eukaryotic organisms involves the transfer of...

Question 12

________ is the process of RNA-mediated inhibition of gene expression.

Accepted Answer

The answer of ________ is the process of RNA-mediated inhibition...

Question 13

In eukaryotes,post-transcriptional control of gene regulation may involve

Accepted Answer

A) alternative mRNA splicing. 
B) control of nuclear export of mRNAs to the cytoplasm. 
C) differential mRNA degradation. 
D) gene amplification and methylation. 
E) alternative mRNA splicing,control of nuclear export of mRNAs to the cytoplasm,and differential mRNA degradation. 
A) alternative mRNA splicing. 
B) control of nuclear export of mRNAs to the cytoplasm. 
C) differential mRNA degradation. 
D) gene amplification and methylation. 
E) alternative mRNA splicing,control of nuclear export of mRNAs to the cytoplasm,and differential mRNA degradation.

Question 14

The genes of the lac operon code for proteins associated with lactose metabolism.Which of the lac gene products is associated with transport of lactose into the cell?

Accepted Answer

A) β-galactosidase 
B) transacetylase 
C) galactoside permease 
D) β-lactase 
E) lactose translocase 
A) β-galactosidase 
B) transacetylase 
C) galactoside permease 
D) β-lactase 
E) lactose translocase

Question 15

Protein phosphorylation,protein folding,and proteolytic cleavage are all examples of

Accepted Answer

A) post-transcriptional control of gene expression and activity. 
B) epigenetic control of inheritance. 
C) repression of gene expression. 
D) induction of gene expression. 
E) post-translational control of gene expression and activity. 
A) post-transcriptional control of gene expression and activity. 
B) epigenetic control of inheritance. 
C) repression of gene expression. 
D) induction of gene expression. 
E) post-translational control of gene expression and activity.

Question 16

DNA rearrangements in eukaryotes can

Accepted Answer

A) cause chromosome puffs. 
B) enhance production of the certain gene products. 
C) increase the diversity of possible gene products from a limited number of genes. 
D) allow for epigenetic regulation. 
E) enhance production of the certain gene products and increase the diversity of possible gene products from a limited number of genes. 
A) cause chromosome puffs. 
B) enhance production of the certain gene products. 
C) increase the diversity of possible gene products from a limited number of genes. 
D) allow for epigenetic regulation. 
E) enhance production of the certain gene products and increase the diversity of possible gene products from a limited number of genes.

Question 17

Gene knockdown via RNAi relies on the ability of eukaryotic cells to

Accepted Answer

A) degrade target mRNAs that are complementary to introduced dsRNA. 
B) induce microRNA expression under particular conditions. 
C) preferentially degrade mutated mRNAs. 
D) inhibit transcription of sets of genes based on the presence of distal control elements. 
E) preferentially degrade mutated mRNAs by inducing microRNA expression under particular conditions. 
A) degrade target mRNAs that are complementary to introduced dsRNA. 
B) induce microRNA expression under particular conditions. 
C) preferentially degrade mutated mRNAs. 
D) inhibit transcription of sets of genes based on the presence of distal control elements. 
E) preferentially degrade mutated mRNAs by inducing microRNA expression under particular conditions.

Question 18

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

Accepted Answer

The answer of Inherited changes in gene expression that are...

Question 19

A lacOc mutant would

Accepted Answer

A) never express lac structural genes. 
B) constitutively express the lac structural genes. 
C) not bind to lacI. 
D) use glucose before using lactose as a carbon and energy source. 
E) not bind to lacI and never express lac structural genes. 
A) never express lac structural genes. 
B) constitutively express the lac structural genes. 
C) not bind to lacI. 
D) use glucose before using lactose as a carbon and energy source. 
E) not bind to lacI and never express lac structural genes.

Question 20

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

Accepted Answer

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

Exam 20: The Regulation of Gene Expression

You are examining an enzyme associated with cysteine biosynthesis.You would expect expression of the enzyme to be

The accompanying graph 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

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

The chromosome of a bacterial cell possesses the following genotype with regard to the lac operon: I−O+Z+Y−A−.This bacterial cell would

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 ________.

Within a genome,an enhancer may be located

A lac I− mutant would

Effector molecules

In eukaryotes,gene amplification is ________ and may occur when ________.

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.

Cloning eukaryotic organisms involves the transfer of a ________ into a cell that lacks one to direct the development of a new organism.

________ is the process of RNA-mediated inhibition of gene expression.

In eukaryotes,post-transcriptional control of gene regulation may involve

The genes of the lac operon code for proteins associated with lactose metabolism.Which of the lac gene products is associated with transport of lactose into the cell?

Protein phosphorylation,protein folding,and proteolytic cleavage are all examples of

DNA rearrangements in eukaryotes can

Gene knockdown via RNAi relies on the ability of eukaryotic cells to

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

A lacOc mutant would

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

A Preview of Cell Biology

The Chemistry of the Cell

The Macromolecules of the Cell

Cells and Organelles

Bioenergetics: the Flow of Energy in the Cell

Enzymes: the Catalysts of Life

Membranes: Their Structure,function,and Chemistry

Transport Across Membranes: Overcoming the Permeability Barrier

Chemotrophic Energy Metabolism: Glycolysis and Fermentation

Chemotrophic Energy Metabolism: Aerobic Respiration

Phototrophic Energy Metabolism: Photosynthesis

The Endomembrane System

Cytoskeletal Systems

Cellular Movement: Motility and Contractility

Beyond the Cell: Cell Adhesions, cell Junctions, and Extracellular Structures

The Structural Basis of Cellular Information: Dna, chromosomes, and the Nucleus

DNA Replication, repair, and Recombination

Gene Expression: Ithe Genetic Code and Transcription

Gene Expression: Iiprotein Synthesis and Sorting

Molecular Biology Techniques for Cell Biology

Signal Transduction Mechanisms: Ielectrical and Synaptic Signaling in Neurons

Signal Transduction Mechanisms: Iimessengers and Receptors

The Cell Cycle and Mitosis

Sexual Reproduction,meiosis,and Genetic Recombination

Filters

The 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 lac ^I−mutant would

In eukaryotes,gene amplification is and may occur when .

A lacO^c mutant would