microbio test 3
which of the following is not applicable to the human papilloma virus (HPV)
HPV possesses a single stranded (+) stranded RNA genome
antisense RNAs do NOT
affect expression of several protein coding genes in a cell
disinfectants and antiseptics have the same application since both reduce microbial numbers
false
which statement is false concerning retroviruses
the information flow of such viruses is DNA to RNA to protein
genomic islands
-contain genes of similar functions -typically represent the flexible gene pool of a bacterial population -may possess genes related to pathogenicity or symbiosis -are typically acquired by horizontal gene transfer (all of the above are correct)
during the secondary step of wastewater treatment
-microbial activity breaks down organic waste -activated sludge is formed (two of the above is correct)
an F prime factor:
-originates from an Hfr strain -contains one or more genes acquired from the chromosome (two of the above are correct
which of the following would be involved in some part of the process of translation of a bacterial gene
-shine-delgarno sequence -polyribosome formation (two of the above are correct)
you have found the D-value of an antimicrobial agent to be 4 minutes when the agent was exposed to a bacterial culture having an initial total viable cell count of 10^9 CFU/mL. after 4 minutes upon addition of the antimicrobial agent, what would have been the total viable count of the culture in this experiment?
10^8 CFU/mL
an F prime factor
A, B and C are all correct -originates from an Hfr strain -represents an infrequent, abnormal excision of an F factor from a chromosome -contains one or more genes acquired from the chromosome
which of the following would not be occurring if transcription of the lactose operon in E. coli was turned off?
A-D would all be occurring in E. Coli -lactose is absent -low levels of cAMP are present in the cell -glucose is present -the lac repressor is active
You have discovered a chemical that possesses antimicrobial properties; further testing of the compound is performed by adding it to a growing bacterial culture. Analysis revealed that, after addition of the chemical, the total viable count of the culture decreased. Without any further information, you would be correct in considering the chemical to be a
Both A and C are possible choices -bacteriolytic agent -bacteriostatic agent -bacteriocidal agent
which of the following is false regarding prokaryotic genes and genomes
DNA sequences such as promoters and operators code for proteins of various functions
how does the M13 filamentous bacteriophage differ from a lytic phage and lysogenic phage
M13 phage can exit its host without killing it
which is true regarding the Enter-Douderoff pathway, the Embden-Meyerhof-Parnas pathway and the Pentos Phosphate shunt?
PPS: primary purpose is to supply building blocks for anabolic pathways
in most bacterial cells, the generation of ATP in the cytoplasm via ATP synthase in the membrane does not require
a higher concentration of protons inside the cell than outside
which of the following is a characteristic of the lytic cycle
a large number of phages are released at a time
a bacterium's genome possesses catabolic genes X, Y, and Z; if it later conjugates and receives a plasmid containing genes X and Y, you would consider this bacterium to be
a partial diploid (genes are expressed as part of the plasmid. aberrant excision and conjugation results in partial diploid bc it doesn't contain all genes)
lysogen occurs in certain bacteria; the equivalent process in an animal cell is best represented by
a retrovirus infection
the attenuation mechanism that helps block expression of the tryptophan operon requires all of the following except
a ribosome stalled at the tryptophan codons of the trp leader transcript
the best description of the initial step in the regulatory process shown below is
a sigma factor mRNA is transcribed and forms secondary structures at lower temperatures. when heated, the structures melt and the mRNA for the heat shock sigma factor, rpoH can be translated.
which among A-D is not a step in the eutrophication process?
all A-D are a part of eutrophication -rapid growth of algae and cyanobacteria -influx of excess nutrients to an aquatic environment, particularly nitrogen and phosphorus -heterotrophic, aerobic respiration -eventual decline in oxygen content of the water
high levels of transcription of the lactose operon require all of the following except
all A-D are required -the presence of lactose -high levels of cAMP -the absence of glucose -the formation of allolactose
the stringent response involves all except
all are involved in the stringent response -reduce expression of rRNA genes -reduce expression of tRNA genes -ATP -GTP
which statement is true regarding prions and viroids
all are true -viruses have capsids composed of protein, whereas viroids have no capsids -prions are infectious protein, and lack nucleic acids -viroids are comprised only of RNA -prions can cause a degenerative neurological disease in humans and other mammals, where viroids primarily infect plants
Bacterium X has acquired an F prime factor from bacterium Y via conjugation. This means that
all of the above -bacterium X has acquired a gene or genes from the chromosome of bacteria Y -Bacterium X now contains a plasmid -a small portion of bacterium Y's chromosome now has a deletion -an F factor was present in bacterium Y's chromosome prior to conjugation
which of the following is not applicable to conjugation
an F factor acquired during conjugation will automatically be integrated into the recipient's chromosome
which of the following is only composed of DNA
an operator
restriction endonuclease and CRISPR sequences are
are ways that a bacterium may protect itself against any viral infection
which statement among A-C is true concerning the M13 filamentous bacteriophage
because of the life cycle it possesses, it can generally always be sure to have a host cell to infect
tegument proteins may be found:
between the capsid and envelope
the regulatory activity of sRNA
can target mRNAs for degradation
inhibition of the metabolism of alternative carbon sources by glucose is called
catabolite repression
when an _____ is bound to a repressor protein, then the repressor is _______ and transcription is minimized or completely blocked
co-repressor, activated
if a gene is always expressed then it is
constitutive
the role of a leader sequence is to
determine whether transcription can proceed through the genes in the operon
a post-translational control mechanism would
directly affect the activity/function of an enzyme or other protein
which statement among A-C is not applicable to flocculation or floc formation during wastewater treatment?
flocculation increases the amount of BOD entering the effluent stream of wastewater (it decreases it)
which of the following is not a method of horizontal gene transfer
formation of daughter cells
which sequence below shows increasing numbers of genes, from least to most, as one proceeds from left to right?
gene, operon, regulon, genome
the primary factor determining the life cycle of an animal virus is the physical form of the
genome
which is applicable to prokaryotic genomes
genomic islands may possess genes related to pathogenicity or symbiosis
when both glucose and lactose are added to the growth medium, E. coli will have a growth curve that
grows, levels off, then grows again
which of the following would not be occurring, if transcription of the lactose operon in E. coli was turned off
high levels of cAMP are present in the cell
what is the relationship between the reduction potential, E, and the change in free energy ^G
if E is positive, then delta G is negative and the reaction is favorable.
which of the following is false regarding an Hfr strain
in an Hfr strain, the F factor exists as a plasmid
which of the following is false regarding an Hfr strain?
in an Hfr strain, the F factor exists as a plasmid.
when an _____ is bound to a repressor protein, then the repressor is ________ and transcription is allowed to occur
inducer ; inactivated
what is the process that turns on the transcription of a gene or genes
induction
transformation:
is a process which may lead to a bacterium becoming a pathogen or resistant to an antibiotic
what is the zone surrounding particles in the disk diffusion method
it is a no growth zone. agents that have large circles around their bacteria are the strongest disinfectant.
which of the following applies to the oxidative catabolism of aromatic compounds such as toluene and other benzene derivatives?
it requires the use of specific deoxygenate enzymes
what is the function of reverse transcriptase in retroviruses
it used viral RNA as a template for DNA synthesis
using the figure above as your guide, along with your knowledge of bacterial genomes, you can be certain that for one of the E. coli cells residing in your gut that
it will have the same 2167 core genes that the other E. coli cells in your gut posesses
using the figure above as a guide, along with your knowledge of bacterial genomes, you can be certain that for one of the E. coli cells residing in your gut that
its genome may compromise one or more plasmids in addition to the chromosome
using the figure above as a guide, along with your knowledge of bacterial genomes, you can be certain that for one of the E. coli residing in your gut that
its genome may compromise one or more plasmids in addition to the chromosome
all of the following typically occur in the presence of high glucose and high lactose concentrations except
lactose is metabolized by the cell (glucose is more favored than lactose)
conjugative transposition is similar to F factor conjugation. which choice below is false regarding the similarity between these two processes
like a transferred F factor, the transposon can maintain a circular form in the recipient cell, separate from the chromosome
which statement is false regarding prions and viroids
like viruses, viroids also possess capsids composed of proteins
what are prions?
misfiled versions of a normal protein
the following are true among A-D concerning transposons except
no exceptions, all A-D comprise all transposons -they have a transposes gene -they possess insertion sequences -they possess inverted repeat sequences -they have the ability to "jump" within the same chromosome
which among A-D is false regarding DNA virus infections and non-retroviral RNA virus infections
non-retroviral RNA viruses generally must enter the nucleus of the host cell before they can infect
which is false regarding recombination?
none are false, all are true. -it can occur between a cell's chromosome and DNA acquired via conjugation, transduction, or transformation -it requires a RecA protein to scan for homology between the chromosome and acquired DNA -it results in formation of holiday structures
which statement among A-D is false regarding animal viral infections
none of A-D are false -uncoating refers to the process of releasing the genome from the viral capsid -depending on the virus type, assembly of viruses may occur in the nucleus or cytoplasm -budding is a mechanism of virus exit that leads to acquisition of the envelope around the viral particles -endosome formation and cell membrane fusion are mechanisms that allow for the uncoating of the virus
which among A-D is false regarding DNA virus infections and non-retroviral RNA virus infections
none of A-D is false, all are true -once inside the host cell, RNA virus replication occurs in the cytoplasm -the genome of DNA viruses generally must enter the nucleus of the host cell they infect -A (+) sense of RNA strand produced by an RNA virus could serve as an mRNA and be directly translated into protein -DNA viruses typically are assembled in the nucleus of the host cell
conjugative transposition is similar to F factor conjugation. which choice among A - D below is false regarding the similarity between these two processes?
none of A-D is false, all are true. -both processes involve donor and recipient cells -unlike a transferred F factor, the transposon cannot maintain a circular form in the recipient cell, it must integrate into the chromosome -like an F factor, the transposon is transferred into another cell in this process -any genes that are a part of the transposon will be transferred into a compatible donor cell
which of the following statements regarding the glycolysis pathway is false?
none of the above are false, they are all true statements -two pyruvate molecules are generated -ATP molecules are generated via substrate-level phosphorylation -it does not require oxygen to operate -ATPs are used in the beginning of glycolysis
in the CRISPR system of bacteria, the spacer is a(n):
piece of phage DNA
the presence of tryptophan (trp) in E. Coli
prevents transcription of the trp structural genes (high levels of trp= no transcription)
most structural genes of bacteria are grouped together and transcribed from a single _____; a _______ refers to control of multiple operons that are typically part of a common metabolism
promoter;regulon
which of the following directly relates to viral trophism
recognition of protein/glycoprotein receptors on the surface of the host cell
which of the following directly relates to viral tropism
recognition of protein/glycoprotein receptors on the surface of the host cell
the -35 and -10 censensus sequences upstream from the transcription start site are
recognized by many sigma factors
which of the following is true of phase variation
recombination leads to an inverted DNA sequence
the _______ is a component of gene regulation that can be in an active or inactive state; it interacts with the ________ region of an operon to influence transcription of genes
repressor;operator
the absence of tryptophan (trp) in E. Coli
results in the formation of an inactive repressor
which of the following is not required for prokaryotic transcription?
shine-dalgarno sequence (it is required for translation)
which mechanism sets the levels of a particular protein in the cell
stability of mRNA transcripts
the diagram represents an overview of metabolism. which statement below is correct regarding the diagram?
the "A" molecules would be larger than the "B" molecules
which of the following among A-D is false regarding phase variation
the DNA sequence is not altered or changed
BOD correlates to
the amount of organic material in water
which statement is false regarding a bacteriophage in the lysogenic cycle?
the bacteriophage will permanently remain in the glycogenic state
which of the following is the best definition of fermentation?
the partial oxidation of glucose with organic molecules such as ethanol and lactate serving as electron acceptors.
which of the following steps is not part of the life cycle of a lytic phage
the phage DNA integrates into the bacterial chromosome
high levels of transcription of the lactose operon require all of the following except
the presence of glucose
a reduction in growth rate that occurs during conditions of nutrient limitation can result in bacteria eliciting _______, a mechanism that helps conserve energy by reducing ribosome formation and assembly via alteration of the transcription of rRNA genes
the stringent response
the formation of the signal molecule ppGpp, the presence of uncharge transfer RNA molecules, and ribosomes stalled during translation all occur as part of
the stringent response
which of the following among A-D is false regarding prokaryotic genes and genomes?
the structural genes of an operon comprise the regulatory sequences that control gene expression
which statement among A-D is false regarding specialized transduction?
theoretically any gene from a bacterial chromosome may be passed from once cell to another by this process
the anti-attenuation mechanism that helps promote expression of the tryptophan operon requires all of the following except
there are no exceptions, all are required -mRNA transcript of the tor leader sequence -a ribosome stalled at the tryptophan codons of the trp leader transcript -formation of an anti-attenuator loop -low intracellular levels of tryptophan
the anti-attenuation mechanism that helps promote expression of the tryptophan operon requires all of the following except
there are no exceptions, all of the following are required -mRNA transcript of the trp leader sequence -a ribosome stalled at the tryptophan codons of the trp leader transcript -formation of an anti-attenuator loop -low intracellular levels of tryptophan
which statement among A-D is not applicable to genomic islands
they are typically acquired by vertical gene transfer
which of the following among A-D is false regarding small regulatory RNAs (sRNAs)
they code for proteins
which statement is not applicable to plasmids?
they replicate only when the cell's chromosome replicates prior to cell division. (they replicate independently of the chromosome)
which statement does not pertain to transposable elements
they require a sex pilus for movement of the transposon
what is the phenotype of an E. coli strain with a mutation in the lac operator that prevents the lac repressor from ever binding? assume glucose is absent
transcription if the operon is very high whether lactose is present or not
in the mechanism of general transduction, any genes from a bacterial chromosome may be passed from one cell to another via a bacteriophage
true
part of the mechanism of specialized transduction resembles the formation of an F prime factor
true
how many of the gene products of the lactose operon are required for the utilization of lactose to occur
two
if a linear segment of DNA acquired by transformation or conjugation with an Hfr strain does not recombine with the host's chromosome, then
two of A, B and C are correct -it will eventually be degraded by the host -it could be used as a food source by the host -it will forever remain in the cell as a linear DNA segment
transformation:
two of the above are correct
a transcriptional control mechanism
two of the above are correct -could involve interaction of a regulatory protein with an operator sequence -would affect the ability of RNA polymerase to carry out its function
which statement is applicable to plasmids
two of the above is applicable to plasmids
a bacterial cell that lacked the Rho protein would be
unable to terminate the transcription of some genes
which statement among A-D is false regarding animal viral infections
uncoating refers to the process of viral exit from the host cell
in E. coli, the passage of traits from parent to daughter cell occurs via
vertical gene transfer
which of the following is false regarding all types of viruses
while outside of the host cell, all viruses can replicate their own DNA or RNA
