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Microbiology
Microbiology
221
Biology
Undergraduate 4
03/24/2019
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Term
Chemical mutagens
 Definition

nucleotide analogs

nucleotide-altering chemicals

frameshift mutagens
Term
Nucleotide analog effects
 Definition
disrupt DNA and RNA replication
Term
X-Rays
 Definition
Cause single- and double-strand breaks in DNA > lethal deletions
Term
Deinococcus radiodurans
 Definition
extremophilic bacterium that is one of the most radiation-resistant organisms known by having multiple copies of its genome (4 circular DNA molecules)
Term
Intercalating agents
 Definition
flat molecules that insert between adjacent base pairs in DNA strand that cause frameshift mutations
Term
Intercalating agent examples
 Definition

Ethidium bromide: used to stain DNA in gels

Chloroquine: used to treat malaria
Term
Auxotroph
 Definition
an organism that requires different nutrients than its wild-type phenotype
Term
Replica plating
 Definition
screens for nutritionally defective mutants - negative (indirect) selection
Term
Prototroph
 Definition
parental strain of auxotroph
Term
Carcinogens
 Definition
cause mutations resulting in cancer
Term
Mutagens
 Definition
increase low frequency of spontaneous reversions
Term
Ames test
 Definition

measures effect of chemical on reversion rate of histidine-requiring Salmonella auxotroph; uses direct selection; if mutagenic, reversion rate increases relative to control

 

 
Term
What does the presence of colonies during an Ames test reveal?
 Definition
the suspected substance is mutagenic in Salmonella
Term
Horizontal gene transfer
 Definition
donor cell contributes part of genome to recipient cell
Term
Transformation
 Definition
naked DNA uptake by bacteria; about 20 genes transferred; sensitive to DNase addition
Term
Transduction
 Definition
bacterial DNA transfer by viruses; small fraction of the chromosome transferred
Term
Bacterial conjugation
 Definition
DNA transfer during cell-to-cell contact (typically involves sex pilus)
Term
Conjugation plasmid transfer
 Definition
entire plasmid transferred
Term
Conjugation chromosome transfer
 Definition
only Hfr cells can be donors; variable fraction of DNA transferred
Term
Thermal death point
 Definition
the lowest temperature that kills all cells in a broth in 10 minutes
Term
An instrument that will come into contact with only the skin of a patient should be disinfected with a...
 Definition
low-level germicide
Term
Which of the following is NOT a desirable characteristic of an ideal antimicrobial agent?
 Definition
it only arrests growth of vegetative cells
Term
Which of the following is a chemical method to control the growth of microbes?
 Definition
surfactants
Term
Chemical methods of microbial control
 Definition

phenols

alcohols

halogens

oxidizing agents

enzymes

antimicrobial drugs

surfactants
Term
Washing dishes in the dishwasher with detergent and hot water is a _____ process
 Definition
disinfecting
Term
Which of the following is the preferred method of determining the efficacy of an antimicrobial chemical in the European Union?
 Definition
the Kelsey-Sykes capacity test: reveals the minimum amount of time required for a particular disinfectant to be effective
Term
Which of the following is a sterilizing agent?
 Definition
peracetic acid
Term
Iodophors and chloramines are similar in that they are both halogen-containing compounds that ____.
 Definition
slowly release their active ingredients.
Term
What effect do aldehydes have on microbial organisms?
 Definition
They damage proteins and DNA
Term
An instrument coming into contact with the skin of an immunocompromised patient should be treated with which of the following?
 Definition
high-level germicide
Term
Compared to moist heat methods, dry heat needs which of the following in order to sterilize effectively?
 Definition
higher temperature and increased time
Term
Long-term storage of milk is made possible by ultra-high-temperature ____.
 Definition
sterilization
Term
The process of filtration is a....
 Definition
sterilizing method.
Term
Which of the following is the most appropriate pairing of microbe and biosafety level?
 Definition
MRSA, BSL-2
Term
Microbial growth in jellies is inhibited by the ____ condition of the food.
 Definition
hypertonic
Term
A scientist develops a new medication that is a protein compound and that must be administered by injection. Which of the following would be the most effective and safest means of preparing a sterile solution of the new medication?
 Definition
filtration
Term
An antimicrobial chemical used on the skin is usually called _____.
 Definition
an antiseptic.
Term
Boiling water for 10 minutes is effective in ridding it of ____.
 Definition
both growing bacteria and enveloped viruses.
Term
Seventy percent alcohol is effective against ____.
 Definition
enveloped viruses.
Term
The decimal reduction time is the time required to kill all the microbes in a given sample - T/F.
 Definition
False
Term
The compound ethylene oxide is used in ____.
 Definition
sterilization.
Term
Which of the following is most susceptible to antimicrobial agents?
 Definition
vegetative bacteria.
Term
Which of the following is a low-level disinfectant?
 Definition
quaternary ammonium compounds (quats)
Term
Which of the following antimicrobial agents is the most toxic to humans?
 Definition
ethylene oxide
Term
Heavy metal and oxidizing agent disinfectants damage ____, interfering with microbial metabolism.
 Definition
enzymes
Term
Disinfectants that damage membranes include ___.
 Definition
both alcohol and phenolics.
Term
Which of the following is used to sterilize items that should not, or cannot, be exposed to heat or water?
 Definition
ethylene oxide
Term
Which of the following is the most difficult to inactivate?
 Definition
bacterial endospores
Term
Hydrogen peroxide does NOT make a good antiseptic for open wounds because ____.
 Definition
catalase in human tissues neutralizes it.
Term
Which biosafety level requires that laboratory air be HEPA-filtered but is insufficient for the safe study of Ebola?
 Definition
BSL-3
Term
Which of the following procedures is currently the standard test used in the United States for evaluating the efficiency of antiseptics and disinfectants?
 Definition
use-dilution test
Term
The phenol coefficient is one of the most widely used measurements of an antimicrobial agent's effectiveness - T/F?
 Definition
False
Term
During production of a drug, all work area surfaces must be disinfected using sterilized disinfectants. Which of the following statements about disinfectants is true?
 Definition

- endospores and viruses can resist disinfectant treatment.

- disinfection can occur by physical or chemical means.

- disinfectants are used to inhibit or destroy pathogens.
Term
Quaternary ammonium compounds are used for __.
 Definition
disinfection.
Term
Betadine contains what type of chemical agent?
 Definition
halogen
Term
Quaternary ammonium compounds are disinfectants effective against ___.
 Definition
enveloped viruses.
Term
Lysozyme is effective against nearly all disease causing agents. -T/F?
 Definition
False
Term
Protozoan cysts are resistant to many disinfection methods. -T/F?
 Definition
True
Term
Which of the following describes flash pasteurization?
 Definition
heating at 72° C for 15 seconds.
Term
Hydrogen peroxide is an effective ____.
 Definition
disinfecting and sterilizing agent.
Term
Antimicrobial agents that damage the viral envelope ___.
 Definition

prevent attachment of the virus to its target cell.

 

Viral envelopes allow the viruses to attach to cells so that they can replicate.
Term
The microbial death rate is ___.
 Definition
constant.
Term
A chemical agent that dissolves lipids can damage ___.
 Definition
cells and enveloped viruses.
Term
Antimicrobial agents usually work best at high temperatures and high pH levels. -T/F?
 Definition
False
Term
Slow freezing is more damaging to microbial cells that quick freezing. -T/F?
 Definition
True
Term
Refrigeration is an effective germicidal method. -T/F?
 Definition
False
Term
Ultra-high temperature sterilization effectively ___.
 Definition
removes all microbes that cause diseases.
Term
Formalin (37% formaldehyde) is used for ___.
 Definition
both disinfection and sterilization.
Term
Natural antiseptics such as pine or clove oil are examples of antimicrobial compounds called ____.
 Definition
phenolics
Term
The ____ are infectious agents most resistant to antimicrobial agents or processes.
 Definition
prions
Term
Alcohols are used for ____.
 Definition
both antisepsis and disinfection.
Term
Order of resistance to antimicrobial agents from least to most resistant:
 Definition

enveloped viruses

gram-negative bacteria

mycobacteria

prions
Term
A nurse preparing a section of skin for an injection is an example of ___.
 Definition

degerming

 

Another example: washing hands
Term
It has been determined that the temperature in an autoclave should reach ____ for sterilization.
 Definition
121° C; 15 psi for 15 minutes to sterilize small volumes.
Term
Which of the following could be used to sterilize objects such as medical devices?
 Definition
ethylene oxide
Term
Which of the following is bacteriostatic?
 Definition
freezing below 0° C
Term
Why are endospores used to measure the effectiveness of autoclave sterilization?
 Definition
Endospores are very hard to kill.
Term
Which of the following techniques can be used to sterilize microbiological media?
 Definition
autoclaving
Term
Gamma irradiation is effective for sterilization because it ___.
 Definition
is penetrating and causes extensive molecular damage.
Term
Which of the following could be used to sterilize a heat-sensitive liquid such as urea broth?
 Definition
filtration
Term
Disinfecting agents naturally produced by microorganisms are
 Definition
antibiotics.
Term
The physical removal of microbes is called ___.
 Definition
degerming
Term
Which of the following would be used to sterilize a mattress?
 Definition
ethylene oxide
Term
By themselves, soaps have only degerming activity, not antimicrobial activity. -T/F?
 Definition
True
Term
Which of the following is NOT a feature associated with filtration?
 Definition

varying thicknesses of membrane filters used

 

Features that ARE associated with filtration:

  • ability of some filters to trap viruses and proteins.
  • sterilization of heat-sensitive materials.
  • nitrocellulose or plastic membrane filters.
  • use of HEPA filters to filter air.
Term
Antimicrobial agents that damage nucleic acids also affect __.
 Definition
protein synthesis.
Term
The process of incineration is used for
 Definition
sterilization.
Term
How does specialized transduction differ from regular lysogeny?
 Definition
The prophage in specialized transduction carries with it pieces of the host chromosomal DNA.
Term
What happens to the packaged DNA of a specialized transduced phage when it infects a new recipient cell?
 Definition
The host DNA integrates, with the prophage, into the new recipient chromosome.
Term
How can specialized transduction contribute to the transfer of antibiotic resistance genes in a bacterial population?
 Definition
The prophage takes an antibiotic resistance gene with it and is packaged with the newly synthesized viral DNA.
Term
How is complex transposon different from simple transposon?
 Definition
They have two simple transposons with another DNA sequence between them.
Term
Why does a complex transposon often contain an extra piece of DNA between the two insertion elements?
 Definition
It is often a gene that confers a survival advantage to the host, such as antibiotic resistance.
Term
How would you be able to determine if the Tn5 transposon you put into a bacterium integrated into the host genome?
 Definition
If the Tn5 transposon integrated into the host genome, the cells would show resistance to the antibiotic kanamycin.
Term
What is the term used to describe bacterial cells that can naturally take up DNA from their environment?
 Definition
competent cells
Term
Which of the following is capable of conjugation?
 Definition
F+ and Hfr cells
Term
Why does conjugation between an Hfr strain and an F- strain not result in two Hfr strains?
 Definition
Conjugation is typically disrupted before the fertility factor can be transferred.
Term
Which of the following is a characteristic of a F+ cell?
 Definition
  • ability to synthesize sex pili
  • presence of a fertility factor
  • ability to mate with an F- cell
Term
What benefit does the F- strain receive from mating with an Hfr strain?
 Definition
It acquires new, potentially beneficial genes from the Hfr strain.
Term
Most bacteria have a natural ability to take up DNA from their environment? -T/F?
 Definition
False
Term
In conjugation, F+ cells
 Definition
contain an F plasmid.
Term
What cellular macromolecule is the fertility factor comprised of?
 Definition
nucleic acid
Term
At which point does a recipient cell become an F+ cell?
 Definition
Formation of the complementary strand of the F factor
Term
Conjugation steps
 Definition
  1. Fusion of the cell membranes
  2. Attachment of the sex pilus
  3. Transfer of the single stranded F factor
  4. Pulling of donor and recipient cells together
  5. Formation of the complementary strand of the F factor
Term
The effects of a transposition event are equivalent to a
 Definition
frameshift mutation.
Term
Which of the following is required for transposition?
 Definition
insertion sequence
Term
Insertion sequences target which areas on a target DNA sequence?
 Definition
A sequence of nucleotides identical to the inverted repeat sequence found on the insertion sequence itself.
Term
What makes an insertion sequence different from other DNA sequences found in a cell?
 Definition
They are capable of effecting their own movement from one location to another on DNA.
Term
How does replicative transposition differ from cut-and-paste transposition?
 Definition

Replicative transposition results in teh transposon being copied to a new location

 

In cut-and-paste transposition, the entire transposon moves to the new location.
Term
Competant cells are cells that
 Definition
can take up DNA from their surrounding environment and integrate it into their own chromosomes by recombination.
Term
What characteristic of the S strain allows it to evade the immune system of the mice?
 Definition
The cells have a capsule.
Term
What most likely explains the recovery of live S strain cells from a mouse injected with heat-killed S strain mixed with live R strain cells?
 Definition
The R strain picked up the S strain DNA, enabling it to produce a capsule.
Term
Which finding is most surprising from Griffith's experiments?
 Definition
S strain cells are isolated from the blood of mice infected with heat-killed S strains and live R strains.
Term
Transfer of random pieces of DNA mediated by phage is known as
 Definition
generalized transduction.
Term
What must occur for bacterial conjugation to take place?
 Definition
The cells must come into contact with each other.
Term
Which statement about conjugation is false?
 Definition

Conjugation is a process of bacterial reproduction.

 

True statements regarding conjugation:

  • E. coli is the model for bacterial conjugation.
  • After conjugation, each cell involved has a copy of the shared DNA.
Term
What is unique about transduction compared to normal bacteriophage infection?
 Definition
Transduction transfers DNA from the chromosome of one cell to another.
Term
How is generalized transduction different from specialized transduction?
 Definition

Generalized transduction is initiated during lytic cycle of a virulent bacteriophage.

 

Specialized transduction is initiated during the lysogenic cycle of a temperate bacteriophage.
Term
A transducing phage
 Definition
contains fragments of the host chromosome instead of the viral genome.
Term
When a transducing phage interacts with a new host cell,
 Definition
the DNA from the previous host can recombine with the new host chromosome.
Term
While studying a bacterial strain, a scientist notes a short DNA sequence between inverted repeats is present in both the chromosome and a plasmid within the cell. This sequence is most likely a
 Definition
transposon
Term
What was the scientific result of Frederick Griffith's experiments with Stretococcus pneumoniae?
 Definition
He showed that the DNA from strain S cells could transform strain R cells.
Term
Frederick Griffith discovered
 Definition
transformation.
Term
In generalized transduction, viruses carry random DNA sequences from one cell to another. -T/F?
 Definition
True.
Term
Bacteriophages are important for which of the following processes?
 Definition
transduction
Term
Which type of transposon would contain a gene for transposase?
 Definition
both simple and complex transposons
Term
How do complex transposons differ from simple transposons?
 Definition

Complex transposons code for additional genetic elements, such as antibiotic resistance genes.

 

Simple transposons only code for the transposase gene essential for the transposon itself.
Term
Antiviral medications frequently block unique ____ to prevent production of a new virus.
 Definition
enzymes
Term
A particular microbe gains resistance to gentamicin. You might also expect this microbe to exhibit resistance against
 Definition

streptomycin.

 

Both are members of the group: aminoglycosides. Both drugs could develop resistance simultaneously through the phenomenon of cross-resistance.
Term
A zone of inhibition measures
 Definition
the effectiveness of a drug.
Term
Most broad-spectrum antibiotics act by
 Definition
inhibiting protein synthesis.
Term
Why do antimicrobial agents active against mycobacteria have to be administered for months or years rather than the typical 10-30 days prescribed to treat other infections?
 Definition

Mycobacteria produce very slowly.

 

Mycobacteria take 12-24 hours to reproduce; in part due to their complex cell walls.
Term
The process of acquiring antibiotic resistance by means of bacteriophage activity is called
 Definition
transduction.
Term
When a nurse rubs your skin with rubbing alcohol prior to administering an injection, what process(es) is he carrying out?
 Definition

Antisepsis and degerming.

 

Rubbing - degerming

Alcohol - antisepsis
Term
Many MRSA strains are sensitive to other antibiotics. Which of the following methods would be the best way to evaluate sensitivity to other antibiotics?
 Definition

disk diffusion.

 

The key point in identifying treatment options for MRSA is to determine which non-beta lactam antibiotics it is sensitive to.
Term
In examining a MRSA strain, researchers find that degraded penicillin is found in the culture medium. What is the most likely mechanism of resistance?
 Definition

Production of beta-lactamase

 

Different MRSA strains can produce beta-lactamases, efflux pumps, and expressed altered PBPs to which beta-lactams cannot bind.
Term
The first antimicrobial widely available for treatment of bacterial infections was a synthetic compound which
 Definition
was an antimetabolic analog.
Term
Prokaryotes contain ____ ribosomes.
 Definition
70S; comprised of 50S and 30S subunits.
Term
Antimicrobial drugs are selectively toxic. This means
 Definition
the drugs are more toxic to the pathogens than to the patient.
Term
The tRNA molecule holding a growing polypeptide chain is at the
 Definition
P site.
Term
Which category of antimicrobial drug works by changing the shape of a ribosome?
 Definition

aminoglycosides

 

An aminoglycoside changes the shape of a 30S subunit causing the ribosome to misread the mRNA.
Term
Which category of antimicrobial drug essentially acts to stall a ribosome as it reads mRNA?
 Definition

macrolides

 

Macrolides block the movement of a ribosome along RNA, so the E site is never emptied and polypeptide formation is stopped.
Term
Chloramphenicol blocks the action of the large (50S) subunit. This essentially ___.
 Definition

prevents the formation of peptide bonds.

 

Without the formation of peptide bonds, amino acids diffuse away and protein synthesis ceases.
Term
Which antimicrobial drugs affect the structure of the ribosome itself?
 Definition

aminoglycosides, antisense nucleic acids, and oxazolidinones

 

Each of these drugs modifies or prevents the formation of the complete 70S ribosome.
Term
The broth dilution test can provide information for determining
 Definition
both the MIC and the MBC (with an additional step).
Term
Disruption of the normal microbiota can result in infections caused by which of the following microbes?
 Definition
both Candida albicans and Clostridium difficile
Term
A drug is structurally similar to PABA and inhibits folic acid synthesis. It is most likely a
 Definition
sulfonamide.
Term
A topical drug ___ inhibits protein synthesis in Gram positive bacteria by preventing loading of isoleucine onto tRNA.
 Definition
Mupirocin
Term
Which of the following drugs inhibits nucleic acid synthesis specifically in most bacteria?
 Definition
fluroquinolones
Term
What can antimicrobial drugs inhibit?
 Definition
  • protein synthesis
  • nucleic acid synthesis
  • formation of the cell wall
Term
Which of the following steps in the folic acid synthesis pathway is specifically inhibited by sulfonamides?
 Definition
the conversion of PABA to dihydrofolic acid
Term
What does MIC stand for?
 Definition
the smallest amount of a drug that will inhibit the growth and reproduction of a pathogen.
Term
What is the correct sequence of the biosynthetic pathway that leads to the formation of DNA and RNA?
 Definition
  1. PABA
  2. dihydrofolic acid
  3. tetrahydrofolic acid
  4. purine and pyrimidine nucleotides
Term
Medications which block viral entry into cells include ___ antagonists.
 Definition
attachment
Term
The outer membrane of Gram-negative bacteria enables many antimicrobial drugs to enter the cell more easily. -T/F?
 Definition
False
Term
Which of the following antifungals works by binding to ergosterol in membranes?
 Definition
both amphotericin B and nystatin
Term
Some bacteria are resistant to erythromycin as a result of mutation of their ribosomal RNA. What type of resistance does this represent?
 Definition
alteration of the target of the drug.
Term
The antimicrobial polymyxin
 Definition
disrupts cytoplasmic membranes.
Term
Some bacteria are resistant to antimicrobials due to the activity of ___, which removes many of them.
 Definition
efflux pumps
Term
Why is polymyxin only used on the skin?
 Definition
It can also damage living human cell membranes, but the drug is safely used on the skin, where the outer layers of cells are dead.
Term
Quinolones and fluoroquinolones act against what bacterial target?
 Definition
DNA gyrase
Term
Which of the following is NOT associated with microbial mechanisms of resistance?
 Definition

denaturation of proteins

 

Proteins are not denatured by antimicrobial drugs.
Term
Some bacterial cells are resistant to a variety of antimicrobials because they actively pump the drugs out of the cell. -T/F?
 Definition
True.
Term
The therapeutic range of an antimicrobial is the
 Definition
range of concentrations at which the antimicrobial is both effective and non-toxic.
Term
Who proposed the concept of chemotherapy, that compounds might selectively kill pathogens without harming people?
 Definition
Paul Ehrlich
Term
Which of the following tests does NOT provide information on the lowest concentration of drug effective on a pathogen?
 Definition

diffusion susceptibility test

 

 
Term
Nucleic acid analog drugs have no effect on human cell replication function. -T/F?
 Definition
False.
Term
Antisense nucleic acids interfere with protein synthesis. -T/F?
 Definition
True.
Term
How does resistance to drugs spread in bacterial populations?
 Definition
Horizontal gene transfer between bacteria spreads R (resistance) plasmids.
Term
Most drugs that inhibit the synthesis of the cell wall act by
 Definition
preventing the cross-linkage of NAM subunits.
Term
What is microbial antagonism?
 Definition

the ability of the normal flora to outcompete and outgrow pathogens.

 

Normal flora is well adapted to its niche. These bacteria may utilize nutrients more quickly or produce bacteriocins that inhibit growth of other microbes.
Term
What is a superinfection?
 Definition
a disease caused by an organism that is often an opportunist or one that was present in low numbers. Superinfection is a sequal to removal of the normal flora by antibiotic treatment.
Term
Which of the following drugs specifically targets cell walls that contain mycolic acid?
 Definition
isoniazid
Term
If a subculture of an MIC test grows in an MBC test, the concentration of the drug was bacteriocidal. -T/F?
 Definition
False.
Term
Antimicrobials that block protein synthesis by binding to the mRNA are
 Definition
antisense nucleic acids.
Term
The mechanism of action of ciprofloxacin is
 Definition
inhibition of nucleic acid synthesis.
Term
The tetracyclines interfere with
 Definition
protein synthesis.
Term
Because all cells engage in protein synthesis, there are few antimicrobial drugs that selectively inhibit this process. -T/F?
 Definition
False.
Term
Semisynthetic drugs developed to combat resistance are often called ___.
 Definition
second generation drugs.
Term
Pentamidine is an example of an antimicrobial
 Definition
effective against eukaryotes, especially protozoa.
Term
The mechanism of action of the antibiotic vancomycin is
 Definition
inhibition of cell wall synthesis.
Term
Which of the following interferes with cell wall synthesis by blocking alanine bridge formation?
 Definition
both cycloserine and vancomycin
Term
AZT and Valaciclovir are antiviral nucleoside analogs that interfere with
 Definition
nucleic acid synthesis.
Term
Drug-resistant populations of microbes arise when
 Definition
exposure to drugs selectively kills sensitive cells, allowing overgrowth of resistant cells.
Term
Which of the following groups of drugs can become incorporated into the bones and teeth of a fetus?
 Definition
tetracyclines
Term
Antimicrobials known as "attachment antagonists" are particularly useful for preventing
 Definition
virus infection.
Term
The ratio of a medication's dose that can be tolerated to its effective dose is the therapeutic ___ of the medication
 Definition
index
Term
Biofilms contribute to the spread of resistance to antimicrobials. -T/F?
 Definition
True.
Term
There are relatively few antifungal medications available compared to antibacterial drugs. -T/F?
 Definition
True.
Term
____ are the most susceptible to the activity of polyene drugs due to the presence of ergosterol in their cytoplasmic membranes.
 Definition
Fungal cells
Term
____ are the least susceptible to polyene drugs because they usually have no sterols in their membranes.
 Definition
Bacterial cells
Term
How might efflux pumps increase antibiotic resistance in bacteria?
 Definition
Resistant bacteria can have more efflux pumps, and can have less specific efflux pumps.
Term
Why is the drug actinomycin used only in research applications or in the treatment of cancer?
 Definition
because it is active against both prokaryotic and eukaryotic cells.
Term
Who discovered the first antimicrobial widely available to the general public?
 Definition
Domagk
Term
Which of the following antimicrobial drugs would likely be useful to treat a MRSA infection because it effectively blocks initiation of translation?
 Definition
oxazolidinones
Term
Beta-lactam antibiotics:
 Definition
  • methicillin
  • penicillin G
  • cephalothin
Term
Some bacteria develop resistance to groups of drugs because the drugs are all structurally similar to each other; this is a phenomenon known as ___ resistance.
 Definition
cross
Term
Which of the following is NOT a target of drugs that inhibit protein synthesis:
 Definition

interference with alanine-alanine bridges.

 

Targets of drugs that inhibit protein synthesis:

  • movement of the ribosome from one codon to the next
  • the tRNA docking site
  • the enzymatic site of the 50S ribosomal subunit
  • the shape of the 30S ribosomal subunit

 
Term
Any drug that acts against a disease is called a ____ agent.
 Definition
chemotherapeutic
Term
Which of the following is an essential component to all viruses?
 Definition
capsid
Term
The envelope found in some virus particles differs from the cytoplasmic membrane of cells in that
 Definition
it does not perform the physiological functions carried out by the cytoplasmic membrane.
Term
What is responsible for the shape of a virion?
 Definition
the capsid
Term
Lysogenic viral DNA
 Definition
Term
Lysogenic viral DNA which has integrated into the host genome is referred to as
 Definition
a prophage
Term
Which of the following events might trigger induction of a temperate bacteriophage?
 Definition
exposure to UV light
Term
How is the lytic cycle different from the lysogenic cycle with respect to the infected host cell?
 Definition
The host cell dies during the lytic stage.
Term
What is the fate of the prophage during the lysogenic stage?
 Definition
It is copied every time the host DNA replicates.
Term
Members of a virus family have the same type of nucleic acid. -T/F?
 Definition
True.
Term
Lysogeny is associated with all of the following EXCEPT ___.
 Definition
animal viruses
Term
Which of the following is correct regarding the viral envelope?
 Definition
It is composed of cellular phospholipid membrane, cellular and viral proteins.
Term
Which of the following statements describes a generalist virus?
 Definition
It infects many kinds of cells in many different hosts.
Term
Which of the following is a characteristic by which viruses are classified?
 Definition
type of nucleic acid
Term
The outermost layer of a virion fulfills which of the following functions of the virus?
 Definition
both protection and recognition
Term
The ____ of a virion determines the type of cell it enters.
 Definition
glycoproteins
Term
The genome of influenzavirus is
 Definition
multiple pieces of linear ssRNA.
Term
A "naked" virus lacks ___.
 Definition
lipid
Term
How are fungal viruses transmitted?
 Definition
as a result of fusion of cells or hyphae
Term
Which of the following virus families has a double-stranded RNA genome?
 Definition
Reoviridae
Term
A lipid membrane is present in which of the following?
 Definition
enveloped viruses
Term
In what ways do viruses differ from other pathogens?
 Definition
viruses lack cytoplasm and organelles.
Term
What is a virion?
 Definition
a single virus particle outside a cell
Term
Host specificity of a virus is due to
 Definition
interactions between viral and cellular surface molecules.
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