Micro Exam 3
Review structure and composition of bacterial cell wall.
-NAM and NAG - Betalactin inhibits cross-linked NAG-NAM chains -Tetrapeptides -Peptidoglycan -Amino acids
Which category of antimicrobial drug works by changing the shape of a ribosome? 1. aminoglycosides 2. tetracyclines 3. oxazolidinones 4. chloramphenicol
1
What is xenotransplantation and its uses?
1. Animal cells, tissues or organs introduced into the human body 2. Example-a person receiving a pig heart
Why are there many antibacterial drugs?
1. Antibacterial drugs constitute the largest number and diversity of antimicrobial agents 2. Selective toxicity
Match each antibiotic (and its functional description) with the appropriate mechanism of action. 1. penicillin 2. trifluridine 3. sulfanilomide 4. gramicidin 5. streptomycin
1. Inhibition of cell wall synthesis 2. Inhibition of DNA or RNA synthesis 3. Inhibition of general metabolic pathway 4. Disruption of cytoplasmic membrane 5. Inhibition of protein synthesis
Enumerate the mode of action of antibacterial and antifungal drugs. Be able to know the examples.
1. Inhibition of cell wall synthesis - susceptible to lysis 2. Inhibition of pathogen's attachment to or recognition 3. Inhibition of DNA and RNA synthesis 4. Inhibition of protein synthesis 5. Disruption of cell membrane 6. Inhibition of metabolism
According to the readings in Chapter 9, which of the following is a chemical method to control the growth of microbes? 1. moist heat 2. desiccation 3. radiation 4. surfactants
4
What is DOT?
Directly Observed Therapy
Why does Dr. Bell start Caleb on HIV therapy in addition to the antibiotics used to treat the tuberculosis?
Dr. Bell prescribes Caleb HIV therapy because the virus is not affected by the antibiotics used to treat tuberculosis.
Chemotherapeutic agents:
Drugs used to treat diseases
What is required by an F- cell to become an F+ cell?
F plasmid
Bacteria can exchange genetic material through conjugation without the need for any protein structures or control mechanisms. Is this statement True or False?
False
Reverse transcriptase synthesizes DNA from a DNA template. True or False.
False
Sub-unit vaccines are made up of whole cells of bacteria or whole viral particle. True or False.
False
Drug-resistant populations of microbes arise when_____
exposure to drugs selectively kills sensitive cells, allowing overgrowth of resistant cells.
If a scientist discovers a new gene, a functional genomic study using __________ may be used to determine what the gene does.
gene knockout
Chlorinating pools is an example of
halogens
Silver creams are examples of
heavy metals
Where are you likely to find an autoclave?
in a dentist office
If you wanted to evaluate a new disinfectant for effectiveness under the conditions of its intended use, the best evaluation technique would be the __________ test.
in-use
Chloramphenicol
inhibits peptide bonding
The ____________ is a defining characteristic of bacteria which is not found in eukaryotes and is therefore a good choice for chemotherapeutic agents.
peptidoglycan cell wall
Replacing the defective gene responsible for sickle-cell anemia is an example of _____
Gene therapy
How is generalized transduction different from specialized transduction?
Generalized transduction is indicated during Lytic cycle of a virulent bacteriophage; specialized is initiated during the Lysogenic cycle of a temperature bacteriophage.
Chloramphenicol blocks the action of the large (50S) subunit. This essentially _____.
prevents the formation of peptide bonds
Mutagens are useful in biotechnology research for
producing organisms with altered phenotypes
What is the effect of pH on the action of antimicrobial agents?
Heat is more effective in acid than alkali, below neutral
How does an F+ cell differ from an Hfr cell?
Hfr strains have the F plasmid integrated into the chromosome.
What are the uses of oxidizing agents?
High-level disinfectants and antiseptics
What is rDNA technology?
Intentionally modifying genomes (DNA) of organisms
What route delivers the antimicrobial drugs to the blood faster?
Intravenous
What is genome mapping?
Involves locating genes on a nucleic acid molecule
What is a nosocomial infection?
It is a hospital-acquired infection.
A fungus inoculated in potato dextrose agar (PDA) is growing until at time X a fungicidal agent is added. What is the effect of the agent to the fungus?
It kills the fungus and does not resume growth if transferred to fresh PDA.
What is bacterial conjugation?
It transfers genetic information via direct cell to cell contact by using a sex or conjugation pilus. Both donor and recipient cell live through this process.
The start codon also codes for which amino acid?
Methionine
What are examples of oxidizing agents?
Peroxide's, ozone, and peracetic acid
What role does pressure play in an autoclave?
Pressure is applied to boiling water to prevent heat from escaping as steam.
What are the most resistant forms of microorganisms?
Prions! They are a protein not a cell. Next one would be endospores.
Tetrahydrofolic acid is needed for the sythesis of ________ which are needed for the synthesis of DNA and RNA in bacteria.
Purines and pyrimidines
In general, how might recombinant DNA technology be used to prevent a genetic disorder caused by a mutation in a single gene?
To insert a desirable gene, remove an undesirable gene, or replace a defective gene with a functioning gene
What is unique about transduction compared to normal bacteriophage infection?
Transduction transfers DNA from the chromosomes of one cell to another
Why are there very few antiviral drugs?
Viruses replicate in the host, so the drugs could affect human cells while trying to destroy viral pathogens.
The process of acquiring antibiotic resistance by means of bacteriophage activity is called
transduction.
Chemotherapy:
treatment of disease with chemical substances
Nucleoside analogues affect which microbes?
viruses
What are the uses of alcohols?
1. Can be used on animate and inanimate surfaces 2. Intermediate-level disinfectants 3. Denature proteins and disrupt cytoplasmic membranes
Prions
1. Cannot be destroyed by sterilization, destroyed by heat and enzymes 2. Mad cow and scrapies are forms of prions 3. VCJD is a disease that humans get when they consume meat that has been contaminated by mad cow disease - prions
Quinolones
1. Ciprofloxacin, ofloxacin 2. Inhibit DNA girase which is needed to correctly replicate bacterial DNA *Antibacterial drug that inhibit nucleic acid synthesis
Lincosamides
1. Clinamycin 2. Binds to 50s ribosomal subunit and stops protein elongation *Antibacterial drug that inhibits protein synthesis
How is E test done? What results can be observed by E-test?
1. Combines MIC and zone of clearing 2. Read number above clearing line
Which statements describe bacterial transformation? -the donor DNA is released into the environment from living bacteria -competent recipient cells are needed -recipient cells that receive the donor DNA die -donor DNA is integrated in the recipient DNA
1. Competent recipient cells are needed 2. Donor DNA is integrated in the recipient DNA
What is meant by structural analogue?
1. Competitive inhibitor 2. A compound having a structure similar to another but, differing compound.
What are examples of method to control microorganisms using dry heat?
1. Complete incineration -1500 C 2. Oven sterilization -1-2 hr at 160-170 C -Hot air
How do drug-resistant bacteria develop?
1. Constant exposure to drugs 2. Drug resistant mutant - sensitive cells are killed by antimicrobial drug - population of drug = resistant mutants over time
Lipoglycopeptide
1. Dalbavancin, oritavancin, vancomycin 2. Interfere wit formation of certain alpine-alanine bridges between NAM subunits *Antibacterial drug that inhibits cell wall synthesis
Enumerate the characteristics of an ideal antimicrobial method
1. Inexpensive 2. Fast-acting 3. Stable 4. Harmless *Does not exist*
Cycloserine
1. Interferes with the formation of alanine-alanine bridges between NAM subunits *Antibacterial drug that inhibits cell wall synthesis
Name some proteins produced by rDNA technology and their uses.
1. Interferons Modified cell: E. Coli Use: to treat cancer, multiple sclerosis, chronic granulomatous disease, hepatitis, and warts 2. Interleukins Modified cell: E. Coli Use: To enhance immunity 3. Tumor necrosis factor Modified cell: E. Coli Use: In cancer therapy 4. Erythropoietin Modified cell: Mammalian cell culture Use: To stimulate red blood cell formation; to treat anemia 5. Human insulin Modified: E. Coli Use: For diabetes therapy 6. Relaxin Modified: E. Coli Use: To ease childbirth
What are the uses of phenols and phenolics?
1. Intermediate to low level disinfectants 2. Examples: Lysol, Triclosan, Cresols 3. Denature proteins and disrupt cell membranes 4. Remain effective in organic contaminants
What are the uses of halogens?
1. Intermediate-level disinfectant and antiseptic chemicals 2. Animate and Inanimate surfaces 3. Damages enzymes by oxidation or denaturation
What is an iodophor?
1. Iodine containing containing organic compound 2. Example: Betadine - used for surgery and injection
What are the techniques of rDNA technology?
1. Polymerase Chain Reaction (PCR) a. Multiply DNA in vitro 2. Gel electrophoresis a. Separating DNA molecules 3. Southern blotting a. Separating DNA molecules 4. Electroporation a. Inserting DNA into cells 5. Protoplasm fusion a. Inserting DNA into cells 6. Gene gun a. Inserting DNA into cells 7. Microinjection a. Inserting DNA into cells
Name examples of antifungal drugs and their mode of action.
1. Polyenes - plasma membrane synthesis and function 2. Azoles - plasma membrane synthesis and function 3. Allyamines - plasma membrane synthesis and function 4. Flucytosin - nucleic acid synthesis 5. Griseofulvin - cell division
Ethambutol
1. Prevents formation of mycolic acid *Antibacterial drug that inhibits cell wall synthesis
What are the mechanisms that made some bacteria developed resistance to antibiotics?
1. Produce enzymes that inactivate the drug 2. Induce changes cell membrane - prevent entry of drug 3. Altering drug's receptor to prevent binding 4. Altering cell's metabolic pathways 5. Pumping the drug out of the cells
Mupirocin
1. Produced by Pseudomonas fluorescens 2. Binds to bacterial tRNAlle synthetase, blocks polypeptide synthesis at isoleucine condons *Antibacterial drug that inhibits protein synthesis
Vaccines
1. Production of safer vaccines (subunit vaccines) 2. Introducing genes of pathogens into common fruits and vegetables 3. Weakened vaccine = attenuated 4. Toxoid = inactivated toxin
Streptogramins
1. Quinupristin, dalfopristin 2. Binds to 50S, stops protein synthesis *Antibacterial drug that inhibits protein synthesis
Explain why the temperature is lower and time is shorter in moist heat sterilization than in dry heat sterilization?
1. Rapid heating means the penetration of heat is faster 2. Plenty of moisture facilitates coagulation of proteins
Enumerate the characteristics of an ideal chemotherapeutic drug? Is there an ideal chemotherapeutic drug?
1. Readily available 2. Inexpensive 3. Chemically stable 4. Easily administered 5. Nontoxic and nonallergenic 6. Selectively toxic agains a wide range of pathogens
Competence in bacterial transformation is the ability of ___ to pick up ___?
1. Recipient cells 2. DNA fragments
What are examples of method to control microorganisms using low temperature?
1. Refrigerator A. 4 C 2. Freezer A. -10 to -20 C B. Ultracold lab freezer typically -80 C
Rifamycins
1. Rifampin, rifaxmin 2. Bind to bacterial RNA polymerase prevents transcription of RNA *Antibacterial drug that inhibit nucleic acid synthesis
Paul Ehrlich (1912): ___________, a treatment for syphilis
1. Salvarsan -form of arsenic -can also be used against African sleeping sickness -effective against Treponema pallidum
How is Kirby Bauer test results interpreted?
1. Wider zone of inhibition = most effective 2. Narrower zone of inhibition = least effective
How is Kirby Bauer test done? What is observed?
1. Zone of inhibition 2. Resistance
Rank the following events in order from GREATEST to LEAST contribution to the spread of antibiotic resistance in bacterial populations.
1. horizontal transfer 2. vertical transfer 3. new mutations
What is the function of the conjugation pilus?
It pulls the F+ and F- cells together.
What is the function of the parental DNA in replication?
It serves as the template for DNA replication.
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?
The R strain picked up the S strain DNA, enabling it to produce a capsule
Compare time and temperature requirement of moist heat sterilization with dry heat sterilization.
The amount of moisture and water depend on the time and temperature of moist heat sterilization. Without moisture and water there is no denaturation which is needed for microbial death
What is water activity(aw)?
The amount of water available for microbial growth
How does the ribosome know if the entering charged tRNA is correct?
The anticodon on the tRNA base pairs to the codon on the mRNA
What is meant if the bacteria are no longer killed by the antibiotics?
The bacteria is now resistant
What happens if cell walls, cell membranes, proteins and nucleic acids are altered/damaged by antimicrobial agents?
Their functions will disrupted and microbes will die -Cell walls = protection -Cell membranes = ATP generation -Proteins = Catalysts
Why are endospores sometimes used in sterility indicators?
They are the hardest life form to kill.
How do restriction enzymes cut DNA sequences?
They cut DNA at sites, called recognition sites, that have specific nucleotide sequences.
How do scientists ensure that autoclaved materials were actually sterilized?
They may place a sterility indicator with a special dye to detect the growth of endospores.
How do nucleotide analogs interfere with DNA replication and transcription?
They work as antimetabolites by being similar enough to the nucleotides to be incorporated into growing DNA strands; but they act as chain terminators and stop viral DNA polymerase.
What is the end goal of PCR?
To quickly increase the number of copies of a specific DNA sequence
Which of the following is an example of horizontal gene transfer in bacteria? -transduction -translation -conjugation
Transduction, conjugation, and transformation
What is the hallmark of all horizontal gene transfers?
Transfer of DNA between organisms of the same generation
Which of the following amino acids is coded by only one codon? -His -Trp -Phe
Trp
By themselves, soaps have not only degerming and no cidal or static activities. True or False.
True
Penicillin is effective only in treating diseases caused by microbes with cell walls composed mainly of peptidoglycan. True or False.
True
Transducing phage are bacterial viruses carrying bacterial DNA. True or False.
True
What are the products of semiconservative replication for a double-stranded DNA molecule?
Two double-stranded DNA molecules, each consisting of one parental strand and one daughter strand.
Half and half cream used inresturants is usually treated by _____
Ultra-high-temperature sterilization
Why is bromine usually used in hot tubs?
Used in hot tubs- because it evaporates less
Which of the following statements regarding vectors is FALSE? -Vectors are usually autonomously replicating DNA molecules. -Cloning vectors include a "marker" to facilitate identification of cells containing them. -Vectors are generally over 100,000 base pairs in size
Vectors are generally over 100,000 base pairs in size
What is the mode of action of dry heat?
Oxidation and reduce to ash
What oxidizing agent is used to disinfect water?
Ozone - O3, can also be used to disinfect grains
During the initiation step of translation, the fMet charged tRNA assembles in which site of the ribosome?
P site
The tRNA molecule holding a growing polypeptide chain is at the _____.
P site
Sulfa drug and PABA would compete for the active site in the enzyme. What happens if PABA is able to bind in the active site?
PABA will make the enzyme needed to make DHF and DNA synthesis occurs.
What oxidizing agent is used to sterilize food processing equipments?
Peracetic acid -sporocide
An R (resistance) plasmid can be transferred from E. coli to Salmonella in culture. Which of the following would suggest that transformation is the transfer mechanism?
Plasmid is not found in the recipient when DNase is added to the culture medium.
A Salmonella virulence operon has three genes that are important for invasion of host cells. These proteins are not produced when the bacteria are growing outside of the host, and are only produced when the bacteria are growing inside the host. Based on this information, how many promoters are there, and what is the mode of regulation?
1; inducible
Why does conjugation between an Hfr strain and an F- strain not result in two Hfr strains?
Conjugation is typically disrupted before the fertility factor can be transferred.
When a nurse rubs your skin with rubbing alcohol prior to administering an injection, what process(es) is he carrying out?
Degerming and Antisepsis
How do gaseous agents kill microorganisms?
Denature proteins and DNA by cross-linking functional groups
How do alcohols control microorganisms?
Denature proteins and disrupt cytoplasmic membranes
What is the mode of action of moist heat?
Denatures proteins and destroys cell membrane and cell wall. In the presence of water.
Cide/Cidal
Destruction of a type of microbe
Which is more effective in killing microorganisms, alcohol diluted with water or undiluted alcohol? Explain.
Diluted!
PABA is needed for the synthesis of ____________ which are needed for the synthesis of tetrahydrofolic acid in bacteria.
Dindrofolic acid
________ can be used to advise prospective parents about their risk of transmitting genetic disorders, such as Huntington's Disease, to their offspring.
Genetic screening
Bt crops, including potatoes and cotton, are genetically engineered using laboratory techniques. Which of the following utilizes recombinant DNA technology to produce advantageous traits in the crops that are produced?
Genetically engineered crops have an advantageous gene from another organism inserted into their genome.
Polymyxin
*Antibacterial drug that alter cytoplasmic membranes
Tetracyclines
1. Doxycycline, tetracycline, tigecycline 2. Prevents tRNA molecules from binding to 30S subunit's docking site *Antibacterial drug that inhibits protein synthesis
What are examples of desiccation methods?
1. Drying 2. Addition of salt 3. Addition of sugar
What is selective toxicity?
1. Effective in killing microbes but do not harm host/human 2. Antibacterial drugs only affect bacterial structures, Prokaryotic, not human structures, Eukaryotic, unlike Antiviral drugs which could affect human structures.
What are the techniques that are used to insert DNA into cells?
1. Electroporation 2. Protoplasm fusion 3. Gene gun 4. Microinjection
Disinfection
1. Eliminate disease causing microbes 2. Inanimate objects
What is reverse transcriptase?
1. Enzyme that catalyze the synthesis of cDNA from an RNA template. 2. The function is to reverse of transcription
What are examples of alcohols?
1. Isopropyl alcohol (70-90%) 2. Tinctures
Bugie and Waksman (1944): _____________
1. Streptomycin
What is the boiling point of water?
100 C
What is the time-temperature requirement of sterilization using autoclave?
121 c for 15-20 minutes
It has been determined that the temperature in an autoclave should reach __________ for sterilization.
121 degrees Celsius
If one were to ascribe to the Five-Second Rule, which of the following places would be the most appropriate place to apply it? 1. a library 2. your home 3. a hospital 4. a school
2
Rank the following point mutations in order of least damaging to most damaging if they occur in the middle of the coding sequence of a polypeptide. 1. Frameshift 2. Missense 3. Nonsense 4. Silent
4, 2, 1, 3
If the water activity of a certain food product is 0.4, what is the ERH?
40%
At which point does a recipient cell become an F+ cell? 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
5
During elongation, how is the RNA synthesized?
5' to 3'
If a spoon has 10,000 of a certain microbe on its surface and you treat it with a germicide that has a D value of 2 minutes, it will take ___ minutes to reduce the number of microbes to 10.
6 minutes
Prokaryotes contain _____ ribosomes.
70S
The cytosol of bacteria contain ____________ which has/have components different from those of the functionally equivalent structure of eukaryotes.
70S ribosomes
What is transferred during bacterial conjugation?
A bacterial plasmid
What is a competent cell?
A cell (recipient) that can take up extracellular DNA from the environment.
What is synthetic nucleic acid?
A machine that can synthesize DNA and RNA
What kind of bond is formed when two amino acids join together?
A peptide bond
What would happen if the mRNA codon that coded for Cys was mutated in the third position from a U to an A?
A stop codon would be introduced prematurely.
What are the four nucleotides in the DNA?
A, G, T, C
What heavy metal is used to treat ophthalmic gonorrhea?
AgNO3 - silver nitrate
Antimicrobial X targets a specific protein in the cytoplasm of the bacterial cell, causing the bacteria to stop growing, but does not kill them. A few bacteria start to grow in the presence of antibiotic X. Analysis of the bacteria that can now grow shows that they have changed the shape of the target for antimicrobial X. What conclusion can be made?
Antimicrobial X is less effective against the new shape of its target.
Water activity is expressed as ____________.
Aw or percent equilibrium relative humidity aw = 1/100 ERH
Which statement about conjugation is false? a. E. Coli is the model for bacterial conjugation b. Conjugation is a process of bacterial reproduction c. After conjugation, each cell involved has a copy of the shared DNA
B.
Sulfa drugs inhibit synthesis of DNA in bacteria. Why can humans taking sulfa drugs synthesize DNA still?
Because humans do not need PABA to make DHF
Why aren't antibiotics effective against the common cold?
Because they are only effective against bacteria, common colds are viral.
Why is autoclaving rather than boiling water used for sterilization?
Boiling water does not kill everything, including bacterial endospores and some protozoan cysts.
The first true antibiotic was __________, which was discovered by __________.
penicillin; Alexander Fleming
If the inserted sequence had been complete except for missing the last 54 nucleotides (and thus the stop signal), would a working protein be possible?
Both yes and no are probable. DNA sequencing after the inserted gene would need to be done to see whether any stop signals would be in the correct reading frame or what possible amino acids would be added to the protein.
Put the following events in the construction of a recombinant DNA molecule in the correct order: a. ligation of desired gene to plasmid DNA b. introduction of the plasmid into bacteria c. restriction enzymes cut gene of interest and plasmid DNA d. growth of cells on an antibiotic-containing medium
C, A, B, D
Competent cells are cells that
Can take up DNA from their surrounding environment and integrate it into their own chromosomes by recombination
What causes thrush?
Candida albicans
What are mutagens?
Chemical or physical agents that will change the DNA
Mice that are injected with only the R strain of Streptococcus pneumoniae
Stay healthy, because their immune systems can kill this strain easily
The process of incineration is used for____
Sterilization
What is the mode of action of low temperature to microbial growth?
Stops or slows growth and decreases metabolism
What are surfactants?
Substances that reduce surface tension of water
What is a superinfection?
Superinfection is a disease caused by an organism that is often an opportunist or one that was present in low numbers. Superinfection is a sequel to removal of the normal flora by antibiotic treatment.
During DNA replication, which nucleotide will bind to an A nucleotide in the parental DNA?
T
Using isopropanol is an example of
alcohols
Which antimicrobial drugs affect the structure of the ribosome itself?
aminoglycosides, antisense nucleic acids, and oxazolidinones
Which category of drug is complementary to mRNA of the pathogen?
antisense nucleic acids
GAU codes for
aspartic acid
The use of lysozyme during the preparation of cheeses and wines is effective in reducing the numbers of
bacteria
R-plasmids are most likely acquired via
bacterial conjugation
Oxazolidinones
block initiation
Antisense nucleic acids
block ribosome attachment
Lincosamides and macrolides
block ribosome movement
Tetracyclines
block tRNA docking
Formalin (37% formaldehyde) is used for
both disinfection and sterilization.
β-lactams group of antibiotics affect the ___ of ___.
cell wall; bacteria
Aminoglycosides
change 30s subunit
What term is used to describe bacterial cells that can naturally take up DNA from their environment?
competent cells
How did the multi-drug-resistant strains of Mycobacterium tuberculosis, like those in the prison, arise?
conjugation and exchange of resistance factors located on plasmids
Drying out fruit to remove water is an example of
desiccation
How do surfactants control microorganisms?
disrupts cell membranes
An oven is an example of
dry heat
Which category of antimicrobial drug essentially acts to stall a ribosome as it reads mRNA?
macrolides
Polymyxin is effective against only some Gram-negative bacteria; therefore, it is considered a __________.
narrow-spectrum drug
Ultraviolet rays that damage microbial DNA is an example of
nonionizing radiation
Which drug for the treatment of tuberculosis inhibits RNA production and colors body secretions red-orange?
rifampin
RNA that has hydrogen bonded to itself forms a
stem loop.
Using soap is an example of
surfactants
RNA polymerase is guided by the
template strand of DNA.
What is microbial antagonism?
the ability of the normal flora to out compete and outgrow pathogens
What is the therapeutic index?
the drug dose the patient can tolerate divided by the effective dose
When a patient is treated with antibiotics, __________.
the drug will kill or inhibit the growth of all of the sensitive bacterial cells
Antimicrobial drugs are selectively toxic. This means _____.
the drugs are more toxic to the pathogens than to the patient
Handwashing with regular soap is effective because __________.
the hydrophobic end of the soap molecule breaks up oily deposits and the hydrophilic end of the molecule attracts water. This combination makes soap a good de-germing agent
What is the purpose of an autoclave?
to sterilize equipment and media
What is the initial target of RNA polymerase?
The promoter
How does specialized transduction differ from regular lysogeny?
The prophage in specialized transduction carries with it pieces of the host chromosomal DNA.
How can specialized transduction contribute to the transfer of antibiotic resistance genes in a bacterial population?
The prophage takes an antibiotic resistance gene with it and is packaged with the newly synthesized viral DNA.
What is the temperature range in the danger zone?
-4 to 60 C
Low level disinfectants/ and antiseptics kill ___________.
-Active-stage Protozoa -gram negative bacteria -fungi -nonenveloped viruses -gram positive bacteria -enveloped viruses
Differentiate antibiotics from semisynthetics?
-Antibiotics only affect bacteria -Antibiotics are nor modified in labs
Antibiotics:
-Biologically produced -Not effective against viruses -Most bacteria and fungi produce them -Stationary phase
What forms of chlorine are used to control microorganisms? Give one use of each form.
-Cl2 -Na/Ca hypochlorite -ClO2 (also a gas, can be used to disinfect air) -Chloramine (can be used to disinfect drinking water)
How do phenols and phenolics control microorganisms?
-Denature proteins and disrupt cell membranes -Remain effective in organic contaminates
How do heavy metals kill microorganisms?
-Denature proteins and interfere with S groups in proteins
What are the methods used to control microorganisms in milk? Describe the temperature-time requirement of each.
-Flash pasteurization A. 72 C for 15 seconds -Ultra-high-temperature pasteurization A. 135 C for 1 second Ultra-high-temperature sterilization A. 140 C for 1-3 seconds
What are the uses of gaseous agents?
-In closed chambers to sterilize items
What are examples of halogens?
-Iodine -Chlorine -Bromine -Flourine
What are the uses of heavy metals?
-Low level -Bacterialstatic -Fungistatic
What is meant by broad spectrum and narrow spectrum antibiotics?
1. Broad spectrum - work against many different kinds of pathogens 2. Narrow spectrum - work against few kinds of pathogens
Review hypertonic solution.
1. Can add salt or sugar 2. Removal of water from cell. 3. Plasmolysis - plasma collapses
Place the various organisms in order from most resistant to least resistant to antimicrobial agents.
-Most resistant 1. prions 2. bacterial endospores 3. cysts of cryptosporidium (protozoan) 4. mycobacteria 5. cysts of other protozoa 6. small nonenveloped viruses 7. active stage protzoa (trophozoites 8. fungal spores 9. most gram negative bacteria 10. vegetative fungi 11. large nonenveloped viruses 12. most gram positive bacteria 13. enveloped viruses -Most susceptible
Intermediate level disinfectants/ and antiseptics kill ___________.
-Mycobacterium -Cysts of Protozoa -Active-stage Protozoa -gram negative bacteria -fungi -nonenveloped viruses -gram positive bacteria -enveloped viruses
What are examples of equipment that use membrane filtration?
-Physically removes microbes -Liquid and air
What are the uses of surfactants?
-Reduce surface tension -low level
GM crops have raised issues among communities in which they are produced. Which of the following are concerns raised by the public about genetically engineered crops?
-The Bt toxin could result in the death of non-pest species of insects. -The Bt toxin could negatively affect the taste of the food that is produced from these crops. -The Bt gene could ultimately make the plants pathogenic to humans.
Alcohols are effective against what microbes? Can alcohol kill endospores?
-bacteria -viruses -fungi -No, they cannot kill endospores
What are examples of gaseous agents?
-ethylene oxide (can sterilized space craft), propylene oxide, β propiolactone
What is an autoclave?
-resembles a pressure cooker -can sterilize (kills endospores) -121 C, 15 psi, 15-20 minutes
What is pasteurization?
-using heat to sterilize food products in a short period of time -63 C for 30 minutes
What is the minimal aw of the following microorganisms? Microbes -Normal bacteria -Normal yeasts -Normal molds -Halophilic bacteria -Xerophilic molds -Osmpohilic yeasts
0.91 = Normal bacteria 0.88 = Normal yeasts 0.80 = Normal molds 0.75 = Halophilic bacteria 0.65 = Xerophilic molds 0.60 = Osmpohilic yeasts
Exposure to which of the following microscopic substances will most likely lead to an allergy in an individual with an over reactive immune system? 1. pollen 2. viruses 3. disinfectants 4. bacteria
1
Which of the following statements is MOST correct regarding the development of antibiotic resistance in populations of bacteria? 1. Exposure to antibiotics selects for the members of a bacterial population which already have a resistant phenotype. 2. Bacteria exposed to antibiotics alter their DNA to become resistant. 3. The bodies of people who take antibiotics become resistant to them.
1
Which of the following statements most accurately describes the principle of selective toxicity? 1. Selective toxicity refers to the ability of an antimicrobial to kill microbes with minimal damage to the host. 2. Selective toxicity refers to the fact that antimicrobial agents target a particular microbial structure, molecule, or pathway to exert their effect. 3. Selective toxicity describes the fact that antimicrobials are more effective against certain microbes compared to others.
1
Which of the following choices correctly matches the class of antibiotic and its mode of action? 1. Aminoglycosides and tetracyclines are inhibitors of protein synthesis. 2. Penicillins and cephalosporins inhibit nucleic acid synthesis. 3. Sulfonamides inhibit the synthesis of essential metabolites. 4. Lipopeptides inhibit cell wall synthesis.
1 & 2
Part B Part complete One approach that is becoming more common in drug D&D is to search for antimicrobial-producing organisms in relatively pristine environments. A pristine environment is one that has been relatively unperturbed by humans and/or domestic animals. Your D&D team is searching for novel antimicrobials produced by bacteria in a remote area of a temperate rainforest in the Pacific Northwest. Which of the following terms would accurately describe your drug? 1. antibiotic 2. chemotherapeutic agent 3. natural 4. semisynthetic 5. synthetic
1, 2, 3
Which of the following contribute to drug resistance in M. tuberculosis? 1. Many individuals fail to complete their entire regimen of antibiotics. 2. Some physicians prescribe the wrong medication, the wrong dosage, or the wrong length of time for treating tuberculosis. 3. In many areas, tuberculosis antibiotics are unavailable or of poor quality. 4. M. tuberculosis is an acid-fast bacterium; this characteristic allows it to become resistant to antibiotics faster than other bacteria.
1, 2, 3
Which of the following correctly describes a method of chemical control used to control microbial growth? 1. Surface-active agents, or surfactants, decrease surface tension among molecules of a liquid. 2. Phenolics exert antimicrobial activity by injuring lipid-containing plasma membranes, which causes the cellular components to leak out of the cell. 3. Alcohols exert their action by denaturing proteins and dissolving lipids. 4. High pressure is used to denature proteins in vegetative cells.
1, 2, 3
What are some side effects resulting from toxicity of antimicrobial agent?
1. Black hair tongue - Fagyl = antiprotozoan drug 2. Yellowing teeth - Tetracyclidine = forms complex with calcium, bad for pregnant women, target 30S ribosomes
Trimethoprim
1. Blocks 2nd metabolic step in formation of folic acid from PABA *Antibacterial drug that are Antimetabolites
What are examples of methods to control microorganisms using moist heat?
1. Boiling: 100 C - kills vegetative cells but endospores survive, can kill in 10 minutes 2. Autoclave gets: 121 C, 15 psi, 15-20 minutes, sterilization, can kill endospores 3. Pasteurization
Use of moist heat can control microbial growth in many circumstances, but heat-sensitive items and those susceptible to moisture cannot be sterilized in this manner. Which of the following correctly describes a method of physical control used to control microbial growth on or in such items? 1. Filtration is the passage of a liquid or a gas through a screenlike material with pores small enough to retain microorganisms. A vacuum is typically used to force the liquid through the mesh, and then the sterile liquid or gas is collected in a sterile container on the other side. 2. Nonionizing radiation, such as UV light, has a wavelength longer than that of ionizing radiation. The wavelengths of UV light are absorbed by cellular DNA in organisms directly exposed to the light. 3. Desiccation is a process that removes water from microorganisms, leaving them unable to grow or reproduce, but still viable. 4. Osmotic pressure is a process that uses high concentrations of salts and sugars to preserve food.
1, 2, 3, 4
If Caleb's strain of M. tuberculosis is sensitive to antibiotic treatment, which of the following could be used to treat his infection? 1. streptomycin 2. penicillins and cephalosporins 3. isoniazid and ethambutol 4. rifampin
1, 3, 4
At each stage of production, sterility of the preparation is a major consideration. When considering appropriate measures to implement to control microbial growth, one must think about the susceptibility of possible microbial contaminants. Apply your knowledge of the structural features of microbes and the mechanisms of action for antimicrobial agents to rank the following microbes according to their susceptibility. 1. prions 2. gram negative bacteria 3. enveloped virus 4. gram positive bacteria 5. endospores
1, 5, 2, 4, 3
By spontaneous mutation which occurs at frequency of ________. Is it a vertical transfer or horizontal transfer?
1. 10 -9 2. Vertical - mother to daughter cell
What is the temperature requirement of a functioning refrigerators, ordinary freezers and lab freezers?
1. 4 C 2. -10 to -20 C 3. -80 C
What is tincture?
1. A medicine made by dissolving a drug in alcohol 2. Iodine
Gramicidin
1. Allows single charged cations to cross freely *Antibacterial drug that alter cytoplasmic membranes
What are the mode of actions of antimicrobial agents?
1. Alteration of cell walls and membranes 2. Damage to proteins and nucleic acid
A Gram-positive bacterial strain is simultaneously treated with two different antimicrobials: Drug A, which targets a protein involved in cell wall synthesis, and Drug B, which targets ribosomes involved in translation. The bacteria continue to grow during the course of treatment, indicating resistance to both antimicrobials. What are all the possible resistance mechanisms this bacterial strain could have?
1. Altered drug target 2. Decreased permeability 3. Drug inactivation 4. Efflux pumps
Name examples of antiviral drugs and their mode of action?
1. Amantadine - viral uncoating 2. Rimantadine - viral uncaoting 3. Nucleoside analogs - nucleic acid synthesis 4. Nonnucleoside polymerase inhibitors - nucleic acid synthesis 5. Nonnucleoside reverse transcriptase inhibitors - nucleic acid synthesis 6. Protease inhibitors - assembly and release of viral particles
Name examples of antimicrobial drugs that inhibit protein synthesis in bacteria. Be able to know the specific action of the drugs.
1. Aminoglycosides 2. Tetracyclines 3. Chloramphenicol 4. Macrolides 5. Antisense nucleic acids
Polyenes
1. Amphotericin B, nystatin 2. Leakage of essential ions from the cell *Antifunal drugs that inhibit cell membranes
Isoniazid
1. Analog of vitamins nicotinamide and pyridoxine; blocks gene for enzyme that forms mycolic acid *Antibacterial drug that inhibits cell wall synthesis
Bacitracin
1. Antibiotic 2. Interferes with movement of peptidoglycan precursors through cell membrane to the cell wall 3. Inhibits RNA transcription 4. Damages bacterial cytoplasmic membrane *Antibacterial drug that inhibits cell wall synthesis
What are vectors?
1. Any agent that carries and transmits an infectious pathogen into another living organism 2. Jumping gene can jump from one to another 3. Viruses: carries gene of interest
Describe the Lytic life cycle.
1. Attachment 2. Entry 3. Bacterial chromosome degraded 4. Synthesis 5. Assembly 6. Release - Host cell dies and releases mature virion
Describe the the Lysogenic life cycle.
1. Attachment 2. Entry 3. Prophage in chromosome 4. Replication of chromosome and cell division 5. Induction 6. Synthesis 7. Assembly 8. Release Parts of it is the Lytic cycle
What are the four levels of safety in labs dealing with pathogens? Describe each.
1. BSL-1 -Handling pathogens that do not cause disease in healthy humans 2. BSL-2 -Handling of moderately hazardous agents -Our Labs! 3. BSL-3 -Handling of microbes in safety cabinets 4. BSL-4 -Handling of microbes that cause severe or fatal disease -Example: Ebola virus
Each phrase below is applicable to a particular mechanism of antimicrobial resistance. Match each phrase to its respective mechanism. 1. drug inactivation 2. efflux pumps 3. decreased permeability 4. altered binding site
1. Bacterial β-lactamases and Antimicrobial altered 2. Antimicrobial moved from inside to outside of cell and Active transport and Turning on transport mechanisms 3. Bacterial porins and Turning off transport mechanisms 4. Structural changes of drug target and Mutation of drug target
Nitroimidazoles
1. Benzidazone, tinidazole 2. Prevent correct DNA replication, aerobic conditions *Antibacterial drug that inhibit nucleic acid synthesis
Vertical Gene Transfer
1. Binary fission of a bacterial cell 2. Mitosis to form two daughter cells 3. Two haploid cells fusing to form a diploid cell
Chloramphenicol
1. Binds to 50s subunits in prokaryotic ribosomes, preventing them from moving along the mRNA *Antibacterial drug that inhibits protein synthesis
Clofazimine
1. Binds to DNA prevents replication and transcription *Antibacterial drug that inhibit nucleic acid synthesis
Place the items associated with decreased exposure to microbes in the bin marked "Decreased Exposure." Place all items associated with increased exposure to microbes the bin marked "Increased Exposure."
1. Decreased Exposure -wiping surfaces with disinfectants -discarding away food that falls on floor -remaining indoors -washing hands regularly 2. Increased Exposure -having pets -sharing food or drink with family -being involved in team sports -gardening outside
What is the mode of action microwave cooking?
1. Denaturation of proteins due to the heat generated 2. Kill bacteria
What are the tests used to determine the sensitivity of antibiotics?
1. Diffusion susceptibility test 2. Minimum inhibitory concentration MIC 3. Minimum bacterial concentration (MBC)
Nisin
1. Disrupts bacterial cytoplasmic membrane produced by Lactococcus lactic *Antibacterial drug that alter cytoplasmic membranes
Pyrazinamide
1. Disrupts membrane transport and prevents Mycobacterium from repairing damaged proteins *Antibacterial drug that alter cytoplasmic membranes
How can we help minimize the development of bacteria resistance to antibiotics?
1. Do not demand antibiotics 2. Use antibiotics as prescribed 3. Don't save antibiotic for next time 4. Never use another person's prescription 5. Only use antibacterial soaps, etc when defenses are weakened
Discuss R plasmid conjugation.
1. Donor has a sex pilus and is antibiotic resistant. Contains R plasmid. The recipient cell has no sex pilus and is antibiotic sensitive. 2. Attachment of donor cell and recipient cell. 3. R plasmid passes one strand from donor cell to recipient cell and it is synthesized 4. Cells detach and 2 cells become antibiotic resistant
What are restriction enzymes?
1. Enzymes that cut DNA at specific sequences and are used to produce recombinant DNA molecules 2 Functions like scissors, cuts at specific location producing blunt or sticky ends
Macrolides
1. Erythromycin, clarithromycin 2. Binds to 50S and prevent elongation of nascent protein
Discuss chromosomal transfer conjugation or Hfr conjugation.
1. F plasmid integrates into chromosome by recombination 2. Cells join via pilus 3. Portion of the F plasmid partially moves into recipient cell, trailing a stand of donor's DNA 4. Conjugation ends with pieces of F plasmid and donor DNA in recipient cell; cells synthesize complementary DNA strands 5. Portions of the plasmid and donor DNA combine with recipient DNA to make recombinant cell, which remains F- because it does not contain a complete F plasmid
Azoles
1. Fluconazole 2. Inhibits synthesis of membrane sterols *Antifunal drugs that inhibit cell membranes
What are some genera of microorganisms capable of producing antibiotics?
1. Fungi 2. Bacteria
Horizontal Gene Transfer
1. Gaining a single new gene sequence from outside of the cell 2. Uptake and insertion of a transposable element carrying foreign genes 3. Infection by a prophage containing a partial bacterial Oberon
What are examples of ionizing radiations? What are their modes of actions?
1. Gamma rays 2. X-rays 3. Splits atoms into ions, break bonds 4. Damage to DNA
What are some applications of rDNA technology?
1. Genome mapping 2. Pharmaceutical and therapeutic application a. Protein synthesis b. Vaccines c. Genetic screening d. DNA fingerprinting e. Gene therapy f. Medical diagnoses g. Xenotransplants 3. Agricultural applications
Assume that you have an antimicrobial agent specific for each of the targets listed below. Indicate which type of microbe would be most susceptible to the agent by placing it in the appropriate bin. 1. Bacteria 2. Gram positive bacteria 3. Viruses 4. All bacteria and viruses
1. Glycolytic enzymes, membrane proteins 2. Peptidoglycan 3. Envelop proteins 4. Nucleic acids
Match the following descriptions of cellular structures with the type of cell in which they are found. 1. Archaea 2. Bacteria 3. Eukaryotes 4. Both Eukaryotes and Prokaryotes 5. Prokaryotes (archaea and bacteria)
1. Hami and Protein cell wall 2. Peptidoglycan cell wall 3. Organelles and 80S ribosome in cytosol 4. Cytoskeleton and DNA and Glycocalyx 5. Fimbriae and 70S ribosome in cytosol
Clostridium difficile is a common healthcare associated infection. It is a Gram-positive spore-forming anaerobe that is associated with antibiotic therapy. It is most commonly transferred between patients on the hands of health care workers. Based on this information, rank the following prevention and control strategies from most beneficial (1) to least beneficial (4).
1. Hand hygiene with soap and water 2. use of gloves 3. Use of approved chemical disinfectants in patient rooms 4. Hand hygiene with alcohol gels
Why are human cells not affected by sulfa drugs?
1. Humans do not use PABA to make purine acide and pyrmidine nucleotides that are required to synthesize DNA and RNA. 2. Humans use folic acid in food
What is genetic screening?
1. Identify genetic disorder in humans 2. Identify DNA of pathogens in the blood or tissues
What is DNA fingerprinting?
1. Identifying individuals or organisms by their unique DNA sequence 2. Can help solve crimes
What is the effect of the presence of organic matter on the action of antimicrobial agents?
1. Inactivate the agents 2. Protect the microbes 3. Interfere with the penetration of the agent
What are the steps of rDNA technology?
1. Isolate plasmid 2. Enzymatically cleave DNA into fragments 3. Isolate fragment with the gene of interest 4. Insert gene into plasmid 5. Insert plasmid and gene into bacterium 6. Culture bacteria a. Harvest copies of gene to insert into plants or animals -Eliminate undesirable phenotypic traits -Create beneficial combination of traits b. Harvest proteins coded by gene -Produce vaccines, antibiotics, hormones, or enzymes
What happens to bacterial cells treated with penicillin? Explain.
1. It will burst 2. Inhibits cross link between peptidoglycan
How can you control growth microorganisms?
1. Killing microbes 2. Inhibiting growth of microbes 3. Removing microbes
Diffusion susceptibility test -What are examples of diffusion susceptibility test?
1. Kirby-Bauer 2. E-test
Oxazolidinones
1. Linezolid, tedizlid 2. Synthetic 3. Inhibits polypeptide synthesis *Antibacterial drug that inhibits protein synthesis
What are the 2 primary types of bacteriophages? How do they replicate?
1. Lytic Bacteriophage - Lytic life cycle (replication process) -> leads to bursting of host cells = new virus cells 2. Temperate Bacteriophage - Lysogenic life cycle (replication process) -> chromosomes are not degraded, viral DNA is injected and mixes with bacterial chromosomes = prophage, cell continues to divide by binary fission which is how the virus lives and spreads, can do the Lytic cycle but the main cycle is the Lysogenic cycle
What can a physician do to minimize the development of bacteria resistance to antibiotics?
1. Making an accurate diagnosis 2. Using appropriate antibiotic combinations 3. Considering use of a narrow spectrum antibiotic in simple infections 4. Urge patient compliance 5. Increase surveillance
What is gene therapy?
1. Missing or defective genes are replaced with normal copies 2. Examples: Cystic fibrosis, sickle cell anemia, hemophilia 3. Process a. Insert normal gene into virus b. Infect bone marrow cell with virus c. Viral DNA inserts into chromosome d. Inject cells into patient
What are the tools of recombinant DNA technology?
1. Mutagens 2. Reverse transcriptase 3. Synthetic nucleic acid 4. Restriction enzymes 5. Vectors
Aminoglycosides
1. Neomycin, streptomycin 2. Inhibits protein synthesis by binding to 30s *Antibacterial drug that inhibits protein synthesis
Match the type of point mutation with the type of damage it is most likely to produce. 1. Silent 2. Nonsense 3. Frameshift 4. Missense
1. No change in gene product. 2. Premature termination of gene product with probable loss of function. 3. Extensive change in gene product structure and function. 4. Small change in gene product which may or may not alter function.
DNA sequencing of an E. coli colony isolated from a nozzle that had biofilm growth of both bacteria shows that conjugation has occurred. However, the transformed strain of E. coli did not express any new proteins. BLAST analysis shows that the gene for the L. monocytogenes protein is incomplete in E. coli. Sequence comparison shows that E. coli has a truncated version of the gene that begins at nucleotide number 54 and continues to nucleotide 1257, meaning that no start codon is present. Why would this interfere with transcription or translation? Select all that apply.
1. No promoter region for the transcription to begin at 2. No start codon for translation
Give examples of nucleotide analogs.
1. Nucleosides which contain a nucleic acid analogue and a sugar. 2. Adenosine analogues: BCX4430 3. Guanosine analogues: abacavir (HIV)
What happens when disease-causing bacteria become resistant to antibiotics?
1. Often cause infection that are more difficult to treat 2. May result in longer and costlier hospitalizations
How is rDNA technology used for medical diagnosis?
1. Patient specimens can be examined for the prescience of gene sequences unique to certain pathogens
Alexander Fleming (1929)_____________
1. Penicillin -accidental discovery -a substance accreted by a mold (Penicillium chrysogenum, a fungus)
Bacta-lactams
1. Penicillins 2. Amoxicillin - semisynthetic 3. Ampicillin - semisynthetic 4. Carbapenems -semisynthetic 5. Cephalothin - cephalosporin, natural 6. Cefotaxime, ceftriaxone, cephalexin - semisynthetic 7. MOA - bind to and deactivate the enzyme that cross-links NAM subunits of peptidoglycan *Antibacterial drug that inhibits cell wall synthesis
What is microbial death? Describe.
1. Permanent loss of reproductive ability (binary fission) 2. Exponential —-1, 2, 4, 8
To understand transduction, study how bacteriophages replicate inside their host cells.
1. Phage injects its DNA (virus) 2. Phage enzymes degrade hosts DNA 3. Cell synthesizes new phages that incorporate phage DNA and mistakenly, some host DNA = Transducing phage 4. Transducing phage injects donor DNA 5. Donor DNA is incorporated into recipient's chromosome by recombination
What are the methods used to evaluate the efficiency of disinfectants and antiseptics? Describe each.
1. Phenol coefficient -no longer used, test compared bacterial activity vs phenol 2. Use-dilution test -Used in USA 3. Kelsey-Sykes capacity test -Europe 4. In-use test -USA 5. Disk-diffusion method -can inhibit the growth by measuring the zone of clearing -wider = more effective
What are the two methods of microbial control? Give examples.
1. Physical method -heat, filtration, refrigeration and freezing, desiccation, osmotic pressure, radiation 2. Chemical method -phenols, phenol is, alcohols, halogens, oxidizing agents, surfactants
Order the following steps from transcription through the initiation of translation.
1. Sigma factor recruits RNA polymerase to the gene promoter on the DNA strand. 2. RNA polymerase begins synthesizing RNA by creating a DNA bubble. 3. Terminator DNA sequences loosen the grip of RNA polymerase and rho causes the release of the DNA strand. 4. The smaller subunit of rRNA attaches at the ribosomal binding site on the mRNA strand. 5. fMET-tRNA binds at the start codon. 6. The larger subunit of rRNA is recruited.
What are the factors that affect the efficacy of antimicrobial agents?
1. Site to be treated a. Home -kitchen vs bathroom b. Hospitals 2. Relative susceptibility of organisms 3. Environmental factors a. Temperature b. pH c. Presence of organic matter
What are the techniques that are used to separate DNA molecules?
1. Southern blotting 2. Gel electrophoresis
By acquiring antibiotic resistance genes. How?
1. Spontaneous mutation - vertical 2. Gene transfer - horizontal
What are examples of organic matter that may affect the action of antimicrobial agent?
1. Sputum 2. Blood 3. Feces 4. Urine *These can activate or stop the penetration of antimicrobial agents.
Discuss plasmid transfer or F+ (male) conjugation.
1. Starts when the "male" (F+), which is the donor cell and contains the plasmid, attaches to the "female" (F-), which is the recipient cell, via pilus. 2. Pilus draws cells together 3. One strand of F plasmid DNA transfers to the recipient. 4. The recipient synthesizes a complementary strand to become an F+ cell with a pilus; the donor synthesizes a complementary strand restoring its complete plasmid.
How do oxidizing agents kill microorganisms?
1. Steal electrons 2. Oxidaze
Botulism food poisoning is a preventable illness if special precautions are taken during food preparation. In this case, what could Sue have done to prevent the outbreak of botulism?
1. Sue noticed that the pressure cooker was malfunctioning during the canning process. She should have fixed the instrument, borrowed a properly working one, or purchased a new pressure cooker. 2. Sue could have boiled the food for at least 10 minutes before serving it to her family members. 3. She could have discarded all of the home-canned food and started over with the same pressure cooker.
Gerhard Domagk (1935): prontosil, a __________
1. Sulfa drug
Sulfonamides
1. Sulfadiazine, sulfadoxine 2. Synthetic 3. Bind to enzyme that produces DHF *Antibacterial drug that are Antimetabolites
What are examples of antimicrobial drugs that are structural analogues of PABA?
1. Sulfanilamide 2. Sulfamethoxazole
Bedaquiline
1. Synthetic 2. Inhibits ATP synthesis enzyme *Antibacterial drug that are Antimetabolites
Dapsone
1. Synthetic analog of paraminobenzoic acid 2. Interferes with folic acid *Antibacterial drug that are Antimetabolites
Allylamines
1. Termina fine 2. Inhibits ergosterol synthesis which is needed for sungai cytoplasmic membranes *Antifunal drugs that inhibit cell membranes
Benjamin Duggar (1948): _______________
1. Tetracycline
What is transduction?
1. The transfer of DNA from 1 bacterium to another with the use of bacteriophage (carrier). 2. Donor DNA is carried by a vector which is a bacterial virus or a bacteriophage.
What are sub-unit vaccine safer?
1. They cannot reproduce in the host 2. Made up of proteins or genes 3. Not cellular 4. Not made up of whole virus
What are the main goals of rDNA technology?
1. To eliminate undesirable phenotypic traits in human, animals, plants, and microbes. 2. To combine beneficial traits of two or more organisms to create valuable new organisms. 3. To create organisms that synthesize products that humans need.
DNA fingerprinting can be used _____
1. To identify bacteria 2. For forensic investigations 3. To determine paternity
What are the routes of administration of antimicrobial drugs?
1. Topical application - on skin 2. Oral - does not stay long in blood 3. Intramuscular - injection in muscle 4. Intravenous - fastest way to deliver drugs to blood and stays longer in the blood
What are the 3 types of gene transfer in bacteria? Is it a vertical transfer or horizontal transfer?
1. Transduction 2. Transformation 3. Conjugation *horizontal transfer - cell to cell, same generation
What is the state of the donor and recipient cells in transduction, translation, and conjugation?
1. Transduction - Donor cell is dead. Recipient cell is alive. 2. Translation - Donor cell is killed by bacteriophage. Recipient cell is alive. 3. Conjugation - Donor cell is alive. Recipient cell is alive.
What are the requirements for transformation, transduction, and conjugation?
1. Transformation - Free DNA environment and a competent and a competent recipient. 2. Transduction - Bacteriophage. 3. Conjugation - Cell to cell and F plasmid (either in cytosol or incorporated into chromosome of donor.
What are the 3 processes of gene transfer in bacteria? Describe each.
1. Transformation - uptake of DNA from environment 2. Transduction - via bacteriophage 3. Conjugation - direct cell to cell
What is an example of non-ionizing radiation? What is its mode of action?
1. Ultraviolet rays 2. Energy is less that ionizing 3. Covalent bonds 4. Damage to DNA
Describe the process of bacterial transformation.
1. Uptake of "naked" DNA from the environment which released from lysed bacterial cells. 2. Donor cell (dead cell) -> DNA -> Recipient cell (competent cell)
What are the two types of gene transfer? Describe each.
1. Vertical transfer = mother to daughter cell (in another generation) 2. Horizontal transfer = cell to cell (in same generation)
Live vaccines
1. Whole viral particles 2. Weakened /no pathogenic 3. Risk that pathogen can revert back to being live and cause the disease a. Weaker individuals
Penicillin's target is transpeptidase, a protein involved in cell wall synthesis. For a Gram-positive bacterium, which of the following mechanisms would be most effective in resisting penicillin's effects? 1. Drug inactivation via β-lactamases 2. Drug inactivation via β-lactamases and altered target binding site 3. Drug inactivation via β-lactamases and use of efflux pumps to move the drug out of the cell
2
The mode of action of alcohol is to denature proteins. Denaturation requires water. Which of these alcohols then, is more effective as antimicrobial agent? 1. 100% alcohol 2. 70-90% alcohol
2
Which of the following activities can be shown to increase resistance among microbial populations? 1. developing second- and third-generation versions of antimicrobial drugs 2. taking antibacterial drugs for viral infections 3. taking a combination of antimicrobial drugs 4. taking an antimicrobial drug for the entire prescribed time
2
Which of the following best explains why the pressure cooker is so important in the canning process? 1. A pressure cooker utilizes normal atmospheric pressure for longer-than-normal cooking times in order to prevent the growth of microbial contaminants and possible endospores. 2. A pressure cooker utilizes steam to create a higher-pressure environment that allows the food to cook at higher temperatures than normal. The higher temperatures kill most contaminating microbes and endospores and therefore effectively sterilize the food.
2
Which of the following is suitable to sterilize a spacecraft? 1. autoclaving 2. exposure to ethylene oxide 3. exposure to UV 4. spraying wiith oxidizing agents
2
Which of the following will most likely contribute to the spread of a genetic mutation among bacterial species? 1. transposition 2. transformation 3. sexual reproduction
2
During production of a drug, all work area surfaces must be disinfected using sterilized disinfectants. Which of the following statements about disinfectants are true? 1. Disinfectants destroy all microbes present on a surface. 2. Disinfectants are used to inhibit or destroy pathogens. 3. Endospores and viruses can resist disinfectant treatment. 4. Disinfection can occur by physical or chemical means. 5. Disinfection can be used to treat work surfaces as well as workers (i.e., washing hands).
2, 3, 4
One alternative to autoclaving for sterilization of liquids is filtration. Imagine that you are using a filter to sterilize a drug solution. You use a filter with a 0.22 μm pore size. Which of the following microbes will effectively be removed by this filter? 1. small viruses 2. bacteria such as E. coli 3. yeast 4. fungi
2, 3, 4
The preferred method of sterilization during drug production is heat. Heat sterilization can occur in two forms: moist or dry. Autoclaving is the most commonly used application of moist heat for sterilization. Which of the following statements about autoclaving is true? 1. When autoclaving solid items, they should be wrapped in foil to help maintain sterility. 2. Autoclaving is preferred over dry heat because it can effectively be used to sterilize a wide variety of items, including liquids, powders, metal instruments, and glassware. 3. The effectiveness of an autoclave is dependent on an increase in pressure and corresponding increase in temperature.
3
Which of the following classifications would best describe Candida albicans? 1. protozoan 2. bacteria 3. yeast 4. RNA virus
3
Which of the following is NOT an important consideration when preparing to use a chemical to disinfect a diaper changing table in a public restroom? 1. The label directions for contact time 2. Whether or not the chemical is compatible with the material that the changing table is made of 3. Whether or not hand sanitizer is available at the changing table 4. Whether or not the changing table is visibly soiled
3
Which of the following mutations would not result in antibiotic resistance? 1. Missense mutation 2. Nonsense mutation 3. Silent mutation 4. Frameshift insertion 5. Frameshift deletion
3
Which of the following statements is NOT true regarding the evolution of antibiotic resistance in bacteria? 1. Bacteria can acquire plasmids conferring resistance through horizontal gene transfer. 2. Resistance can emerge due to mutations in chromosomal genes. 3. The exposure of bacteria to an antibiotic causes the bacteria to produce resistance genes. 4. Due to natural genetic variation within populations, resistant bacteria will be present--even in the absence of antibiotic.
3
Which of the following statements is true about disinfectants? 1. They are all effective in destroying endospores. 2. they are used on living tissues. 3. They are used on inanimate surfaces. 4. They are used for sterilization.
3
Which among the following cell features of bacteria are potential targets for Dr. Ehrlich's "magic bullets" due to significant difference or absence from humans? 1. Cytoskeleton 2. DNA 3. Ribosome 4. Cell wall
3 & 4
Many MRSA strains are sensitive to other antibiotics. Which of the following methods would be the best way to evaluate sensitivity to other antibiotics? 1. Gram stain 2. Assay for a PBP2a allele 3. Growth on high salts 4. Disk diffusion
4
Which of the following could be used to sterilize objects such as medical devices? 1. orthophenylphenol 2. 100% alcohol 3. silver nitrate 4. ethylene oxide
4
Which of the following is an INCORRECT pairing? 1. chloramine: disinfects water supplies 2. bromine: disinfects hot tubs 3. chlorine dioxide: disinfects buildings 4. iodophor: alcohol solution of iodine, applied to skin
4
Which of the following point mutations is most likely to alter a protein product without destroying its function? 1. Silent 2. Nonsense 3. Frameshift 4. Missense
4
Bacterial conjugation is often referred to as bacterial sex. Why is this term inaccurate?
Conjugation does not result in the formation of new offspring
A strain of E. coli has been isolated from a patient with serious diarrhea. In addition to its chromosome, it has a plasmid. Strains that lose the plasmid become non-pathogenic, and non-pathogenic strains are able to cause diarrhea if transformed with the plasmid. What type of plasmid is this?
A virulence plasmid
Which of the following is a characteristic of an F+ cell? -Presence of a fertility factor -Ability to mate with an F- cell -Ability to synthesize sex pili, presence of a fertility factor, and ability to mate with an F- cell.
Ability to synthesize sex pili, presence of a fertility factor, and ability to mate with an F- cell.
What heavy metal used to kill algae in swimming pools?
Algicide - CuSO4
High level disinfectants/ and antiseptics kill ___________.
All microbes including endospores
What is the key difference between donor cells and recipient cells?
An F plasmid
Why is DNA replication essential for a cell?
An organism must copy its DNA to pass genetic information to its offspring.
Why does the physician start Caleb on the antibiotic azithromycin before laboratory results come back?
Antibiotic therapy is started with a broad-spectrum antibiotic because broad-spectrum antibiotics are effective against many gram-positive and many gram-negative bacteria.
Why are there few antifungal drugs?
Both human and fungal cells are Eukaryotic which can affect human structures as well as the fungal structures.
Semisynthetics:
Chemically modified antibiotics
Drugs:
Chemicals that affect anatomy/physiology in any manner
What is meant by selective toxicity?
Chemotherapeutic agents should act against the pathogen and not the host.
Be able to know how to determine MIC?
Clearest tube = lowest concentration
Synthetics:
Completely synthesized in the lab
A transducing phage
Contains fragments of the host chromosome instead of the viral genome
Which of the following is NOT used by bacteria to acquire new genetic material? -crossing over -transduction -conjugation
Crossing over
Quinolones and fluoroquinolones act against what bacterial target?
DNA gyrase
The molecule that seals the gaps between the pieces of DNA in the lagging strand is
DNA ligase
Which of the following attaches the target gene to a desired location? -DNA ligase -Plasmids -Restriction enzymes
DNA ligase
Which statement about DNA replication is FALSE? -DNA ligase adds nucleotides to the lagging strand. -The two strands of parental DNA are separated during DNA replication.
DNA ligase adds nucleotides to the lagging strand.
Which of the following build(s) new strands of DNA? -Parental DNA -The lagging strand -DNA polymerases
DNA polymerases
Synthetic nucleic acids are useful as
DNA probes, primers, and antisense RNAs.
How do halogens kill microorganisms?
Damages enzymes by oxidation or denaturation
Membrane filtration is a ____ method of achieving sterilization.
Degerming
Hfr is a cell that has given away its F plasmid. True or False.
False
Is penicillin effective in growing cells or in older cells? Explain.
Growing cells because they are forming the cross link chains so it is easier to inhibit that instead of trying to destroy they ones that are already made in older cells.
What is the effect of temperature on the action of antimicrobial agents?
Higher temperature - faster death of microbes
How can hospital personnel prevent the spread of resistant Enterococcus faecium throughout the hospital?
Hospital personnel should wash their hands when entering and leaving a patient's room.
Why are chemotherapeutic agents that work on the peptidoglycan cell wall of bacteria a good choice of drug?
Humans and other animal hosts lack peptidoglycan cell walls.
What oxidizing agent is used to clean deep wounds?
Hydrogen peroxide -danger of tetanus -our cells have catalyze which breaks down hydrogen peroxide to water and oxygen
Why do containers of liquid placed in an autoclave need to remain at least slightly open?
If they remain closed, they may implode.
Where would one find an uncharged tRNA molecule in a ribosome?
In the P and E sites
How would one increase the concentration of a particular polypeptide in a cell?
Increase the level of transcription
Stasis/static
Inhibiting but not complete destruction of a type of microbe, slows growth
What is the action of penicillin on bacterial cell wall?
Inhibits synthesis of bacterial cell walls
How does desiccation control microorganisms?
Inhibits the growth and disrupts metabolism
Bt crops are engineered in the lab to produce Bt toxins due to the presence of a bacterial gene from B. thuringiensis. Why is it advantageous for the plants to produce the Bt toxin?
Insects that normally destroy non-toxin-producing crops will be killed when they eat plants that do produce the toxin.
A recombinant cell
Is a cell that receives DNA from an outside source and incorporates it into its own
What benefit does the F- strain receive from mating with an Hfr stain?
It can acquire new, potentially beneficial genes from the Hfr strain.
Why is polymyxin only used on the skin?
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.
Why would a recombinant DNA molecule be inserted into a host cell?
It can be copied, transcribed, and translated into a desired protein.
Minimum inhibitory concentration (MIC) -What is MIC?
Lowest concentration of the drug that prevents the growth of organism in vitro
Minimum bactericidal concentration (MBC) -What is MBC?
Lowest concentration that kills 99.9% of bacteria
What are examples of phenols and phenolics?
Lysol, Triclosan, Cresols
Which of the following is NOT a goal of recombinant DNA technology? -Making it possible to clone humans -Creating organisms capable of producing useful products -Eliminating undesirable traits from livestock or crops -Combining genetic material from more than one organism to produce new useful organisms -Being able to remove or correct damaging traits in humans
Making it possible to clone humans
What is gene transfer?
Mechanisms for uptake of DNA to create variability
Describe how a laminar flow biological safety cabinet works to control microorganisms?
Membrane filter moves air away from you, and traps MO to sterilize the air
Differentiate water activity of food from moisture content of food?
Moisture content = total moisture (amount of free and bound water)
What does MDR mean?
Multi-drug-resistant
Be able to know how to determine MBC?
No growth on plated media
Sulfa drug and PABA would compete for the active site in the enzyme. What happens if sulfa drug is able to bind in the active site of the enzyme?
No synthesis of DHF and synthesis of DNA stops
Can you use penicillin to treat fungal diseases? Explain.
No, because it is specific to inhibiting NAM-NAG chains in the bacterial cell walls. Fungi does not have peptidoglycan.
Can you use penicillin to treat diseases caused by mycoplasmas? Explain.
No, because they do not have cell walls.
What cellular macromolecule is the fertility factor comprised of?
Nucleic acid
In examining a MRSA strain, researchers find that degraded penicillin is found in the culture medium. What is the most likely mechanism of resistance?
Production of a beta-lactamase
What is meant by microbial control?
Reduction in numbers and activity
Gegerming
Removal of microbes by mechanical means. -Hand washing -Alcohol swabbing at site of injection
Antisepsis
Removal of pathogens from living tissue
Sanitation
Removal of pathogens from objects to meet public health standards. -Washing silverware in scalding water in restaurants
Which of the following enzymes can make specific cuts in DNA molecules? -Reverse transcriptase -Restriction enzymes -DNA ligase
Restriction enzymes
Which of the following is an application that uses PCR?
Sequencing a gene, diagnosing a disease, and providing enough DNA for cloning into another organism
What heavy metal is used to treat burns?
Silver sulfadiazine
How many codons code for the amino acid arginine?
Six
What are examples of surfactants?
Soaps - determine agents 1. Antibacterial = added Triclosan Detergents 1. Quats - Benzalkonium chloride 2. Example: BacDown in lab
A researcher mistakenly uses a heat-sensitive version of DNA polymerase in a PCR. Which of the following will occur?
The PCR will stop after one cycle.
When using the autoclave to sterilize materials, what happens to temperature as the pressure is increased?
Temperature increases as well
Which of the following best explains how scientists are able to introduce the bacterial gene for Bt toxin into the cotton plant genome? -The Bt toxin gene is isolated and inserted into a Ti plasmid from Agrobacterium tumefaciens. The engineered Ti plasmid is taken up by a bacterium that infects the cotton plant. -A virus is engineered to contain the Bt toxin gene. This virus is then used to infect the plant and pass on the gene. -The bacterial gene for Bt toxin is isolated, and the DNA is put into tiny bullets (like BB's) that are "shot" into the cotton plant using a gene gun.
The Bt toxin gene is isolated and inserted into a Ti plasmid from Agrobacterium tumefaciens. The engineered Ti plasmid is taken up by a bacterium that infects the cotton plant.
When a transducing phage interacts with a new host cell
The DNA from the previous host can recombine with the new host chromosome
What is meant when a bacterium is said to become "resistant" to an antibiotic?
The bacterium is neither killed nor inhibited by the antibiotic.
What characteristic of the S strain allows it to evade the immune system of the mice?
The cells have a capsule
What must occur for bacterial conjugation to take place?
The cells must come into contact with each other
If the patient were to get a subsequent urinary tract infection, what should the doctor prescribe knowing that she is susceptible to thrush?
The doctor should prescribe an antibiotic specific for the bacterial species causing the urinary infection.
What was the MOST likely source of the family's botulism food poisoning?
The family consumed botulism toxin in the canned green beans.
How does genotype determine phenotype?
The genotype gives instructions for the structural, enzymatic, and regulatory proteins which result in the phenotype.
When using the autoclave to sterilize materials, which kill the microorganisms, the high temperature or the pressure?
The high temperature
What happens to the packaged DNA of a specialized transduced phage when it infects a new recipient cell?
The host DNA integrates, with the prophage, into the new recipient chromosome.
Which statement about DNA replication is CORRECT? -The leading strand is one of the strands of parental DNA. -The lagging strand is one of the strands of parental DNA. -The leading strand is built continuously, and the lagging strand is built in pieces.
The leading strand is built continuously, and the lagging strand is built in pieces.
Pasteurization
The process of treating foods and beverages with heat to destroy or slow the growth of pathogens
Sterilization
The process that completely destroys all microbial life, including endospores.
A microbiastatic agent would be effective on _____
Vegetative bacterial cells
Compare susceptibility of vegetative cells with endospores to antimicrobial agents.
Vegetative cells are more susceptible compared to endospores
Why is it difficult to find good chemotherapeutic agents against viruses?
Viruses depend on the host cell's machinery, so it is hard to find a viral target that would leave the host cell unaffected.
How is translation terminated?
When a protein called a release factor enters and binds to the A site
In temperatures important in food safety, what is meant by danger zone?
Where pathogens that affect humans grow
What are examples of heavy metals?
Zn (Zinc), Hg (Mercury), Ag (Silver), Cu (Copper)
Strachan suggested the "hygiene hypothesis" in 1989, although his idea is almost impossible to demonstrate experimentally. Since Strachan's hypothesis is almost impossible to demonstrate using experimentation, how did he most likely arrive at such an assertion?
by comparing cases of allergy-associated disorders from years past to those of the present
PCR stands for
polymerase chain reaction
Which of the following procedures is currently the standard test used in the United States for evaluating the efficiency of antiseptics and disinfectants?
use-dilution test
