MB 351 Exam 2

Which of the following structures is responsible for the run and tumble movements observed in motile bacteria? a. Flagella b. Pili c. Autoinducer d. Cilia

Flagella

Most prokaryotic transcriptional units have one or more regulatory sites controlling the rate of transcription.

True

Prokaryotic cells exclusively convert nitrates to N2 gas.

True

Prokaryotic genomes contain multiple transposons and insertion sequences.

True

Purple sulfur bacteria grown in stagnant, anoxic waters using hydrogen sulfide for energy.

True

Quorum sensing induces expression of operons involved in biofilm, surfactant and antibiotic production.

True

Recombination is a separate process from replication in a prokaryotic cell.

True

Sea floor methane hydrate is metabolized through a syntrophic relationship between methanotrophic archaea and sulfate-reducing bacteria.

True

Since Hfr formation is reversible, every Hfr or F+ culture is a mixture of both.

True

Specialized transduction can be used to understand the cis/trans nature of a regulatory region or protein.

True

Spirochetes are characterized by their periplasmic endoflagella.

True

Syntrophy is common in anaerobic freshwater ecosystems.

True

The high viscosity of most bacterial environments results in little to no coasting when bacteria engage in a tumble.

True

The nitrifying bacteria are mostly obligate chemoautotrophs capable of oxidizing ammonia or nitrite for energy.

True

The sulfate-reducing bacteria are ubiquitous in anaerobic environments and predominant in marine sediments.

True

There are two types of bacterial transcription termination - Rho-dependent and Rho-independent.

True

The host-pathogen relationship is an example of what type of symbiosis? Select one: a. commensalism b. parasitism c. mutualism

b

What is the function of the Xis protein in heterocyst development? Select one: a. Xis determines heterocyst spacing. b. Xis acts as a transcription factor to turn on expression of nifD and fdxN. c. Xis fixes nitrogen gas into ammonia. d. Xis performs two irreversible DNA rearrangements.

d

Which drawing in the figure represents the pathogenic bacterial species responsible for syphilis, Lyme disease, and relapsing fever?

(a. spirochete)

Which of the following is NOT true of genetic diversity? a. Genetic diversity is created in prokaryote populations by mutation and horizontal gene transfer. b. All genetic changes are beneficial because they increase genetic diversity. c. Genetic diversity can lead to advantageous adaptions to changing environmental conditions. d. Transformation, conjugation, and transduction all create genetic diversity.

All genetic changes are beneficial because they increase genetic diversity.

Which of the following is NOT a feature of prokaryotic classification? a. All of the these are features of prokaryotic classification. b. None of the these are features of prokaryotic classification. c. Since prokaryotes do not reproduce sexually, they are not grouped by species using the same criteria as eukaryotes. d. Horizontal gene transfer among prokaryotes makes genetic classification more difficult. e. Prokaryotes are grouped based on differences in their 16s rRNA sequence.

All of these are features of prokaryotic classification.

In the presence of arabinose, a. AraC acts as a transcription factor to turn on transcription of the genes for arabinose synthesis. b. AraC acts as a repressor to turn off transcription of the genes for arabinose synthesis. c. AraC binds the effector, arabinose, and acts as a transcription factor. d. AraC binds the effector, arabinose, and acts as a repressor.

AraC binds the effector, arabinose, and acts as a transcription factor.

Which of the following are advantages to biofilm formation? (select all that apply) a. Biofilms prevent quorum sensing. b. Biofilms decrease horizontal gene transfer. c. Biofilms protect microbial cells from predation by eukaryotic microbes. d. Attachment to a solid surface prevents cells from being washed out of a flowing habitat.

Attachment to a solid surface prevents cells from being washed out of a flowing habitat., Biofilms protect microbial cells from predation by eukaryotic microbes.

This term describes a bacterium that has the capacity to take up DNA via transformation.

Competent

If E. coli is grown in liquid media containing equal amounts of glucose and lactose, which sugar will the bacteria use as a carbon source?

E. coli will use the glucose until it is depleted and then begin to use the lactose.

A parasitic symbiotic relationship is detrimental to both partners.

False

Anaerobic niches in marine or freshwater sediments are typically devoid of significant organic material, and therefore facilitate colonization by carbon and nitrogen fixing organisms only.

False

Assimilatory nitrate reduction (nitrate to ammonia) is an exclusively prokaryotic process.

False

Changes in heterocyst nitrogenase genes are reversible under high oxygen conditions.

False

DNA gyrase overwinds the archaeal chromosome into a positive supercoil.

False

Deinococci are the only bacterial lineage to lack peptidoglycan entirely, having a protein cell wall.

False

E.coli cells moves in the direction of increasing attractant concentrations via a random walk.

False

Ectomycorrhizae produce haustauria, which penetrate through plant root cell walls - growing into the root cells.

False

Free-swimming chemotactic bacteria power their transmembrane flagella motors with ATP.

False

Most prokaryotic transcriptional units are under the control of strong promoters to allow rapid, dynamic genetic response to changes in environment.

False

Plasmids replicate by the rolling circle mechanism before conjugation.

False

Polycistronic mRNA contains transcriptional control sequences for ribosome binding and translational termination.

False

Prokaryotic genomes typically have 25-50 nucleotides between genes.

False

Proteins recognize the difference between DNA base pairs viewed from inside the DNA helix but not from outside of the DNA helix.

False

Purple sulfur bacteria grown in stagnant, anoxic waters using organic sulfur for energy.

False

Quorum sensing allows cells to begin production of certain compounds only upon reaching a certain size.

False

Rhizobium bacteriods provide fixed nitrogen for the water fern Azolla, leading to increased rice crop yields.

False

STARI is a red, expanding "bulls eye" lesion around a lone star tick bite caused by Borrelia burgdorferi.

False

Sigma proteins assist RNA polymerase with promoter binding in all prokaryotes and dissociate after transcription initiation.

False

Specialized transduction can transfer DNA across great evolutionary distances.

False

Strains of E. coli either contain the F plasmid (F+) or lack the F plasmid (Hfr).

False

The genes controlling conjugal plasmid transfer are normally expressed.

False

The spoA cascade is initiated by a series of sigma factors.

False

The sulfate-reducing bacteria are found wherever organic matter is decomposing aerobically.

False

Transcription of a bacterial operon leads to a single mRNA and a single polyprotein, which is then cleaved into individually functional proteins.

False

Transformation is when DNA - released by a competent cell - is taken up by a donor cell.

False

This transmembrane protein binds chemoattractant and initiates a signaling pathway that alters flagella rotation.

MCP

The binding of an effector molecule to a repressor protein activates the repressor protein to bind DNA. What form of transcriptional control will result?

Negative control of a repressible operon.

Bacterial DNA genes are arranged in a(an) _____________, which allows for coordinated control of transcription of those genes.

Operon

What disease causes a rash, a red, expanding "bulls eye" lesion around a tick bite, followed by fatigue, fever, headache, muscle and joint pains?

Southern Tick Associated Rash Illness

Cells carrying a plasmid will not conjugate with other cells containing the same plasmid. What is the term for this phenomenon?

Surface exlusion

In lecture 20, you were prompted to watch a video of Dr. Bonnie Bassler discussing an example of quorum sensing using the Hawaiian bobtail squid and its symbiont, Vibrio fischeri . Each morning the squid pumps out 95% of the bacteria present in the light organ. Why? a. The squid senses that the concentration of autoinducer has become too low. b. The bacterial population in the light organ had reached saturation and is beginning to die. c. The squid senses that the concentration of autoinducer has become too high. d. The bacteria begin to turn on virulence genes that could harm the squid.

The bacterial population in the light organ had reached saturation and is beginning to die.

Which of the following best describes the regulation of the lac operon? a. The lac repressor is bound to the lac operator in the absence of lactose. b. The lacI repressor is an effector molecule that regulates transcription of the lac operon. c. Lactose binds the promoter and helps initiate transcription of the lac operon. d. The lac repressor is bound to the lac operator in the presence of lactose.

The lac repressor is bound to the lac operator in the absence of lactose.

Molecular chronometers provide evidence of evolutionary relatedness while avoiding the confusion of convergence.

True

DNA gyrase underwinds the bacterial chromosome into a negative supercoil.

True

Deinococci are known for their extreme radiation and ultraviolet (UV) light resistance.

True

Heterocysts lose photosystem II and undergo significant morphological differentiation.

True

Host legume symbiosome cells produce leghemoglobin molecules to maintain a low oxygen concentrations for Rhizobium bacteriods.

True

Irreversible DNA rearrangements occur in the mother cell during endosporulation.

True

Microbial waste products accumulate in high concentrations near the cells and low concentrations a few millimeters away.

True

Which of the following statements is CORRECT about bacterial transcription? a. A single RNA polymerase produces all RNA transcripts. b. Rho protein is required for termination of transcription. c. The mRNA is extensively modified before transcription. d. Various sigma factors recognize different promoter sequences. e. It occurs in the periplasm.

Various sigma factors recognize different promoter sequences.

A Vibrio fischeri species, Vibrio strain A, produces an autoinducer molecule incapable of binding LuxR. What conclusion can you draw about Vibrio strain A?

Vibrio strain A present in the light organ of a bobtail squid will be unable to produce light.

Which of the following are characteristics of dead zones? (select all that apply) Select one or more: a. A dead zone is a low oxygen or hypoxic area in an ocean or lake. b. Water containing too much dissolved oxygen causes most marine animal life to die or flee. c. The northern Gulf of Mexico has one of the largest dead zones in the world. d. Dead zones are exclusively the result of human activity. e. The purple bacteria are found in anaerobic environments like marine dead zones. f. Algael digestion of the microbial life can quickly deplete the dissolved oxygen in the water.

a, c, e

Of the following statements, what is TRUE of the transport between the heterocyst and adjacent vegetative Anabaena cells. (select all that apply) Select one or more: a. The amino acid glutamine is transported from the heterocyst to the adjacent vegetative cells. b. Ammonia is transported from the heterocyst to the adjacent vegetative cells. c. Vegetative cells provide ATP directly to heterocyst cells. d. Vegetative cells provide sucrose to feed the core metabolic energy pathways of the heterocyst cell to generate ATP.

a, d

Which of the following ecosystems are anaerobic? a. marine sediment b. intestinal tract c. freshwater sediment d. marine water column e. freshwater water column

a. marine sediment b. intestinal tract c. freshwater sediment

What is the predominate group of microbes in freshwater sediments? Select one: a. methanogens b. aerobic and sulfate-reducing microbes c. sulfate-reducing microbes d. methanogens and sulfate-reducing microbes e. aerobic microbes

a. methanogens

In the endospore formation cascade, SpoOA (select all that apply) a. acts as a transcription factor. b. turns on synthesis of sigma factor H. c. is phosphorylated by KinB. d. is the sensor that becomes phosphorylated.

acts as a transcription factor., turns on synthesis of sigma factor H.

The legume's roots excrete a mixture of chemical compounds into the soil that function (select all that apply) Select one or more: a. to act as a chemorepellent to non-symbiotic strains of bacteria. b. to begin to establish symbiosis. c. to kill parasitic bacteria in the soil environment. d. to act as a chemoattractant to specific strains of rhizobium bacteria.

b, d

In the Azolla/Anabaena symbiotic relationship, cyanobacterial nitrogen fixation supports the growth of ________. a. only the Anabaena fern b. both the Azolla cyanobacteria and the Anabaena fern c. both the Azolla fern and the Anabaena cyanobacteria d. only the Azolla cyanobacteria

both the Azolla fern and the Anabaena cyanobacteria

What greenhouse gas is also a common end-product of many microbial fermentations? a. carbon dioxide b. nitrogen gas c. sulfate d. hydrogen sulfide

carbon dioxide

What form of sulfur can be used as an electron acceptor in anaerobic respiration? Select one: a. hydrogen sulfide b. No form of sulfur is used as an electron acceptor in anaerobic respiration. c. sulfite d. sulfate

d. sulfate

The horizontal gene transfer process known as transduction

involves a virus.

Termination of bacterial transcription (select all that apply)

is Rho-independent - does not require the Rho protein and relies on specific sequences in the mRNA., is Rho-dependent - requires the Rho protein to displace RNA polymerase.

A phage concatemer (select all that apply) a. is packaged into the virus capsid using a headful mechanism. b. refers to a sequence in the host genome where the phage genome is inserted. c. refers to copies of the host genome that are packaged into the virus capsid. d. refers to multiple, contiguous copies of the phage genome.

is packaged into the virus capsid using a headful mechanism., refers to multiple, contiguous copies of the phage genome.

Ruminants provide __________ to their microbial symbionts, and then absorb the products of symbiont __________.

nutrients, fermentation

The bacterial chromosome is

usually circular and found in a nucleoid.