Question 1

The stringent response downregulates rRNA synthesis. Does it similarly downregulate ribosomal protein synthesis?

Accepted Answer

Ribosomal protein synthesis will also slow, but not due to ppGpp and the stringent response. Ribosomal proteins have the ability to bind to their own mRNA, and when they do, translation is inhibited. Binding to their own mRNA only happens when rRNA concentrations drop, thereby increasing cytoplasmic levels of free ribosomal proteins. These ribosomal proteins bind to their mRNAs and effectively shut down translation.

Question 2

Explain how a repressor protein works with respect to a biosynthetic operon.

Accepted Answer

When the end product of the biosynthetic operon is high, the cell does not need those enzymes. Thus, the end product will bind to the inactive aporepressor and become an active repressor protein, which will shut down the transcription of the genes. As the end product gets low, there is not enough to bind to the aporepressor; thus, there will be no repression, and transcription of the needed genes will occur.

Question 3

When both glucose and lactose are added to the growth medium, Escherichia coli will have a growth curve that

Accepted Answer

A)  does not change. 
B)  grows slowly and then, halfway through, grows faster. 
C)  grows, levels off, and then grows again. 
D)  grows more slowly than with glucose alone. 
E)  grows more quickly than with glucose alone. 
A)  does not change. 
B)  grows slowly and then, halfway through, grows faster. 
C)  grows, levels off, and then grows again. 
D)  grows more slowly than with glucose alone. 
E)  grows more quickly than with glucose alone. C

Question 4

One benefit of operons in bacteria is that they

Accepted Answer

A)  allow for alterations in DNA sequence by flipping promoters around. 
B)  allow for coordinated gene expression of related genes on one mRNA controlled by one promoter. 
C)  do not need ligands and regulatory proteins as single genes would. 
D)  do not need any modification of the proteins after they are expressed. 
E)  allow for the bacteria to utilize a wide variety of carbon sources. 
A)  allow for alterations in DNA sequence by flipping promoters around. 
B)  allow for coordinated gene expression of related genes on one mRNA controlled by one promoter. 
C)  do not need ligands and regulatory proteins as single genes would. 
D)  do not need any modification of the proteins after they are expressed. 
E)  allow for the bacteria to utilize a wide variety of carbon sources.

Question 5

What happens when strand slippage occurs on the template or the newly synthesized DNA strand? How does Neisseria gonorrhoeae use slipped-strand mispairing to its advantage?

Accepted Answer

Strand slippage occurring on the templat

Question 6

Some microbes use gene regulation to periodically change their appearance, in a process called

Accepted Answer

A)  sporulation. 
B)  attenuation. 
C)  regulation. 
D)  activation. 
E)  phase variation. 
A)  sporulation. 
B)  attenuation. 
C)  regulation. 
D)  activation. 
E)  phase variation.

Question 7

In terms of controlling chemotaxis, the proteins involved control chemotaxis in which way?

Accepted Answer

A)  They control which form of flagellin is expressed. 
B)  They change the direction of the flagella from counterclockwise to clockwise and back. 
C)  They promote longer "tumbles" when a chemoattractant is present. 
D)  They increase the phosphorylation of CheY so that there are more counterclockwise flagella. 
E)  They respond to demethylation of methyl-accepting chemotaxis proteins to bring about longer runs. 
A)  They control which form of flagellin is expressed. 
B)  They change the direction of the flagella from counterclockwise to clockwise and back. 
C)  They promote longer "tumbles" when a chemoattractant is present. 
D)  They increase the phosphorylation of CheY so that there are more counterclockwise flagella. 
E)  They respond to demethylation of methyl-accepting chemotaxis proteins to bring about longer runs.

Question 8

The figure below diagrams a process used to study bacterial physiology. Which is the correct description of the steps shown?

Accepted Answer

A)  Cells are lysed, two-dimensional gels are run, and then spots of protein are run through mass spec. Proteins' peaks are identified. 
B)  Cells are lysed, two-dimensional gels are run, isobaric tags are added to the proteins, and they are run through a mass spec. Proteins' peaks are identified. 
C)  Cells are lysed, two-dimensional gels are run, and proteins are digested with trypsin and run through a mass spec. Proteins' peaks are identified. 
D)  Cells are lysed, proteins are digested with trypsin, and column is used followed by mass spec. Proteins' peaks are identified. 
E)  Cells are lysed, RNA is purified, cDNA is made, and sequencing is carried out. 
A)  Cells are lysed, two-dimensional gels are run, and then spots of protein are run through mass spec. Proteins' peaks are identified. 
B)  Cells are lysed, two-dimensional gels are run, isobaric tags are added to the proteins, and they are run through a mass spec. Proteins' peaks are identified. 
C)  Cells are lysed, two-dimensional gels are run, and proteins are digested with trypsin and run through a mass spec. Proteins' peaks are identified. 
D)  Cells are lysed, proteins are digested with trypsin, and column is used followed by mass spec. Proteins' peaks are identified. 
E)  Cells are lysed, RNA is purified, cDNA is made, and sequencing is carried out.

Question 9

When an inducer is added to a medium containing an organism with a metabolic pathway controlled by a repressor, the inducer then

Accepted Answer

A)  combines with the repressor and activates the repressor. 
B)  combines with the repressor and inactivates the repressor. 
C)  combines with the substrate and blocks induction. 
D)  combines with the substrate and activates induction. 
E)  does not combine with, but functions as a chaperone molecule for, the enzyme-substrate complex. 
A)  combines with the repressor and activates the repressor. 
B)  combines with the repressor and inactivates the repressor. 
C)  combines with the substrate and blocks induction. 
D)  combines with the substrate and activates induction. 
E)  does not combine with, but functions as a chaperone molecule for, the enzyme-substrate complex.

Question 10

As diagrammed below, some amino acid biosynthetic operons have stem loop structures in the mRNA. These structures play a role in the regulation of the operon by which of the following mechanisms?

Accepted Answer

A)  The leader sequence shown contains codons for the amino acid. When these are low, the ribosome stalls, allowing a hairpin between the two middle regions to form so that the rest of the message can be translated. 
B)  A repressor protein made of that amino acid will bind to the region and prevent translation when large amounts of the amino acid are present. 
C)  In the presence of large amounts of the amino acid, the hairpin will wind around the amino acid and prevent further translation. 
D)  The uridine-rich region has codons for that amino acid; when present, this region will be a terminator region. The hairpins allow for an RNA to bind that then allows translation to occur. 
E)  Catabolite repressor protein can bind and prevent the hairpins from forming, thus allowing translation to occur. 
A)  The leader sequence shown contains codons for the amino acid. When these are low, the ribosome stalls, allowing a hairpin between the two middle regions to form so that the rest of the message can be translated. 
B)  A repressor protein made of that amino acid will bind to the region and prevent translation when large amounts of the amino acid are present. 
C)  In the presence of large amounts of the amino acid, the hairpin will wind around the amino acid and prevent further translation. 
D)  The uridine-rich region has codons for that amino acid; when present, this region will be a terminator region. The hairpins allow for an RNA to bind that then allows translation to occur. 
E)  Catabolite repressor protein can bind and prevent the hairpins from forming, thus allowing translation to occur.

Question 11

Bacterial systems using an AraC/XylS-type regulator include ________ as regulated by ________.

Accepted Answer

A)  a type III secretion system in Pseudomonas; NitR 
B)  a type III secretion system in Pseudomonas; ExsA 
C)  a type III secretion system in Pseudomonas; YbtA 
D)  virulence genes and cholera toxin in Vibrio; TxtR 
E)  virulence genes and cholera toxin in Vibrio; ExsA 
A)  a type III secretion system in Pseudomonas; NitR 
B)  a type III secretion system in Pseudomonas; ExsA 
C)  a type III secretion system in Pseudomonas; YbtA 
D)  virulence genes and cholera toxin in Vibrio; TxtR 
E)  virulence genes and cholera toxin in Vibrio; ExsA

Question 12

Explain the process of attenuation in regulating transcription of the tryptophan operon.

Accepted Answer

Attenuation is a process of transcriptio

Question 13

Which genes always occur in intergenic regions?

Accepted Answer

A)  tRNA 
B)  mRNA 
C)  sRNA 
D)  rRNA 
E)  tsRNA 
A)  tRNA 
B)  mRNA 
C)  sRNA 
D)  rRNA 
E)  tsRNA

Question 14

A transmembrane sensor kinase protein senses an environmental condition outside ________ bacteria or in the periplasm of a(n) ________ bacteria.

Accepted Answer

A)  Gram-positive; Gram-negative 
B)  Gram-negative; Gram-positive 
C)  prokaryotic; eukaryotic 
D)  prokaryotic; archaean 
E)  Gram-positive; acid-fast 
A)  Gram-positive; Gram-negative 
B)  Gram-negative; Gram-positive 
C)  prokaryotic; eukaryotic 
D)  prokaryotic; archaean 
E)  Gram-positive; acid-fast

Question 15

Explain what happens to motility when a chemoattractant is added to bacterial cells.

Accepted Answer

In the presence of a chemoattractant, th

Question 16

If the newly synthesized DNA strand slips back relative to the template strand, one copy of the repeated unit is ________ the growing strand.

Accepted Answer

A)  inserted in 
B)  deleted from 
C)  folded over 
D)  folded under 
E)  bound to 
A)  inserted in 
B)  deleted from 
C)  folded over 
D)  folded under 
E)  bound to

Question 17

The AraC regulator both activates and represses transcription of the genes involved in arabinose catabolism. How is this system more advantageous to a cell than a simpler repressor system like that used on the lac operon?

Accepted Answer

The repressor in the lac operon comes co

Question 18

With respect to quorum sensing, all of the following are true EXCEPT that it

Accepted Answer

A)  can be involved in cross-talk between species, including eukaryotes. 
B)  can be involved in some pathogenesis and biofilm formation. 
C)  has only one autoinduction system per species. 
D)  is carried out with an autoinducer such as homoserine lactone. 
E)  plays a role in some antibiotic production. 
A)  can be involved in cross-talk between species, including eukaryotes. 
B)  can be involved in some pathogenesis and biofilm formation. 
C)  has only one autoinduction system per species. 
D)  is carried out with an autoinducer such as homoserine lactone. 
E)  plays a role in some antibiotic production.

Question 19

Which of the following describes the process of obtaining RNA sequence information?

Accepted Answer

A)  Proteins are isolated and mass spec is used. Once the proteins are known, the RNA that coded for them can be determined. 
B)  RNA from a particular growth condition is isolated and converted to cDNA; DNA adapters are added, allowing high-throughput sequencing to be carried out. The genome position of the sequence obtained is then determined using computer software. 
C)  A DNA microarray is used to find the RNA sequences expressed at that time. 
D)  One examines the tRNA and rRNA in a given culture in order to study various physiological conditions. 
E)  One determines the RNA sequence of every gene in the genome and then determines if it is present in a given culture. 
A)  Proteins are isolated and mass spec is used. Once the proteins are known, the RNA that coded for them can be determined. 
B)  RNA from a particular growth condition is isolated and converted to cDNA; DNA adapters are added, allowing high-throughput sequencing to be carried out. The genome position of the sequence obtained is then determined using computer software. 
C)  A DNA microarray is used to find the RNA sequences expressed at that time. 
D)  One examines the tRNA and rRNA in a given culture in order to study various physiological conditions. 
E)  One determines the RNA sequence of every gene in the genome and then determines if it is present in a given culture.

Question 20

Quorum sensing plays a role in interspecies communications. Describe the relationship between green seaweed Enteromorpha and Vibrio anguillarum bacterial cells in biofilms, and explain how Escherichia coli was used to understand this interaction.

Accepted Answer

Enteromorpha makes motile zoospores that

Exam 10: Molecular Regulation

The stringent response downregulates rRNA synthesis. Does it similarly downregulate ribosomal protein synthesis?

Explain how a repressor protein works with respect to a biosynthetic operon.

When both glucose and lactose are added to the growth medium, Escherichia coli will have a growth curve that

One benefit of operons in bacteria is that they

What happens when strand slippage occurs on the template or the newly synthesized DNA strand? How does Neisseria gonorrhoeae use slipped-strand mispairing to its advantage?

Some microbes use gene regulation to periodically change their appearance, in a process called

In terms of controlling chemotaxis, the proteins involved control chemotaxis in which way?

The figure below diagrams a process used to study bacterial physiology. Which is the correct description of the steps shown?

When an inducer is added to a medium containing an organism with a metabolic pathway controlled by a repressor, the inducer then

As diagrammed below, some amino acid biosynthetic operons have stem loop structures in the mRNA. These structures play a role in the regulation of the operon by which of the following mechanisms?

Bacterial systems using an AraC/XylS-type regulator include ________ as regulated by ________.

Explain the process of attenuation in regulating transcription of the tryptophan operon.

Which genes always occur in intergenic regions?

A transmembrane sensor kinase protein senses an environmental condition outside ________ bacteria or in the periplasm of a(n) ________ bacteria.

Explain what happens to motility when a chemoattractant is added to bacterial cells.

If the newly synthesized DNA strand slips back relative to the template strand, one copy of the repeated unit is ________ the growing strand.

The AraC regulator both activates and represses transcription of the genes involved in arabinose catabolism. How is this system more advantageous to a cell than a simpler repressor system like that used on the lac operon?

With respect to quorum sensing, all of the following are true EXCEPT that it

Which of the following describes the process of obtaining RNA sequence information?

Quorum sensing plays a role in interspecies communications. Describe the relationship between green seaweed Enteromorpha and Vibrio anguillarum bacterial cells in biofilms, and explain how Escherichia coli was used to understand this interaction.

Microbial Life: Origin and Discovery

Observing the Microbial Cell

Cell Structure and Function

Bacterial Culture, Growth, and Development

Environmental Influences and Control of Microbial Growth

Viruses

Genomes and Chromosomes

Transcription, Translation, and Bioinformatics

Gene Transfer, Mutations, and Genome Evolution

Viral Molecular Biology

Biotechniques and Synthetic Biology

Energetics and Catabolism

Electron Flow in Organotrophy, Lithotrophy, and Phototrophy

Biosynthesis

Food and Industrial Microbiology

Origins and Evolution

Bacterial Diversity

Archaeal Diversity

Eukaryotic Diversity

Microbial Ecology

Microbes in Global Elemental Cycles

Human Microbiota and Innate Immunity

The Adaptive Immune Response

Microbial Pathogenesis

Microbial Diseases

Antimicrobial Therapy

Clinical Microbiology and Epidemiology

Filters

Bacterial systems using an AraC/XylS-type regulator include as regulated by .

A transmembrane sensor kinase protein senses an environmental condition outside bacteria or in the periplasm of a(n) bacteria.