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134 Cards in this Set
- Front
- Back
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What is biotechnology? |
Use of cells &/or biologic molecules to solve problems or make useful products |
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What is genetic engineering? |
Intentionally modifying genomes of organisms |
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What is recombinant DNA technology? |
Intentionally modifying genomes of organisms |
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What are the goals of genetic engineering? |
--Eleminate undesirable phenotypic traits --Combine beneficial traits of >1 organism --Create organisms that synthesize products humans need |
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Why are plasmids useful in genetic engineering? |
Bacteria can naturally pick up plasmids from their environment or other bacteria |
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What are restriction enzymes? |
Enzymes that recognize & cut both strands of DNA molecule at specific restriction site |
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What is DNA ligase? |
Enzyme that facilitates joining of DNA strands together |
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What is a blunt end? |
Result when restriction enzyme cuts both DNA strands at the same point |
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What is a sticky end? |
Result when restriction enzyme cuts both DNA strands at different points |
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What is the advantage & disadvantage of a blunt end? |
Advantage: blunt ends are nonspecific Disadvantage: more difficult to make recombinant DNA from because ends aren't sticky |
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What is the advantage & disadvantage of a sticky end? |
Advantage: easier to make recombinant DNA because ends are sticky Disadvantage: requires specific complementary sticky end to make recombinant DNA |
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What is gel electrophoresis? |
Method of sorting DNA molecules based on size |
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How does gel electrophoresis work? |
DNA moves in an electrical field because negatively charged phospates move towards positive poles when electricity is applied |
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How are recombinant plasmids copied & expressed in bacteria? |
1. Plasmid isolated 2. Plasmid cleaved into fragments 3. Fragment w/ gene of interest isolated 4. Isolated gene inserted into plasmid 5. Recombinant plasmid inserted into bacterium 6. Bacteria cultured |
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What is a vector in molecular cloning? |
DNA molecule used as a vehicle to artificially carry foreign genetic material into a cell where it can be replicated &/or expressed |
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What is polymerase chain reaction (PCR)? |
Technique by which scientists produce a large number of identical molecules of DNA in vitro |
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What are the steps involved in a polymerase chain reaction cycle? |
1. Denaturation: exposure to heat separates target DNA strands 2. Priming: cooling in presence of complementary DNA primers added to target DNA, aiding polymerase with DNA synthesis 3. Extension: warming increases rate at which DNA polymerase replicates each strand to produce more DNA. |
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What is the advantage of polymerase chain reaction cycling? |
Exponentially increases number of DNA molecules replicated |
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What is the Southern technique? |
Method of transferring DNA from agarose gel to less delicate nitrocellulose membranes |
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What are Southern blots used for? |
--Genetic fingerprinting --Diagnosing infectious diseases |
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What is restriction fragment length polymorphism (RFLP)? |
Utilization of nucleic acid "probes" to find a specific sequence in a complex mixture |
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What is DNA fingerprinting? |
Identifying individuals or organisms by their unique DNA sequences |
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How is DNA fingerprinting carried out? |
1. Procure sample of DNA 2. Make copies via PCR 3. Cut copies w/ restriction enzymes 4. Separate fragments using gel electrophoresis 5. Create Southern blot of pattern 6. Compare Southern blot against known patterns |
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What is a retrovirus? |
Virus that integrates its genes into host chromosomes |
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What is genomics? |
Sequencing & analysis of genome nucleotide bases |
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How do scientists hope studying pathogen genomics will benefit humans? |
--Develop novel drugs --Develop more effective therapies & vaccines |
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How do scientists hope genomics will elucidate protein function? |
--Increase DNA resistance to radiation --Increased understanding of psychrophiles & food processing applications |
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What is bioinformatics? |
Use of computers & IT to analyze (sequence) biological information |
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What is sterilization? |
Removal/destruction of all microbes |
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What is aseptic? |
Environment/procedure that is free of contamination by pathogens |
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What is antisepsis? |
Disinfection of skin or other tissue via chemicals |
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What is sanitization? |
Process of disinfecting places & utensils to be used by the public to reduce # of pathogenic microbes to acceptable public health standards |
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What is disinfection? |
Reduction in # of pathogenic organisms to the point where they don't pose danger of disease |
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What factors determine choice of antimicrobial procedure? |
--Site to be treated --Relative susceptibility of microorganisms --Environmental conditions |
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How do mechanisms for controlling microbes work? |
--Damage cell wall/membrane --Denature proteins --Damage nucleic acids |
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What is the Kirby-Bauer test? |
Antibiotic wafers are applied to a culture to determine microbe susceptibility & measurement of ring of inhibition is indicator of effectiveness |
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What is the decimal reduction time (DRT)? |
The amt. of time it takes to kill 90% of a microbial population |
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How is moist heat used to control microbial growth? |
--Denatures proteins --Interferes with integrity of cell membranes & cell walls --Disrupts structure & functions of nucleic acids |
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Why is moist heat more effective that dry heat at controlling microbial growth? |
Water is a better conductor of heat than air |
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What are methods of controlling microbial growth that utilize moist heat? |
--Boiling --Autoclaving --Pasteurization --Ultra-high temperature sterilization |
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How is dry heat used to control microbial growth? |
--Denatures proteins --Fosters oxidation of metabolic & structural chemicals |
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What is flash pasteurization? |
High temperature, short time (HTST) - 72°C for 15 sec |
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What is ultra-high temperature pasteurization? |
Flash heating milk & other liquids to 140°C for 1-3 seconds & then cooling rapidly to eradicate all living microbes |
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What is refrigeration? |
Method of decreasing microbe metabolism, growth, & reproduction by reducing temperatures |
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What is freezing? |
Method of inhibiting microbial metabolism by formation of ice crystals that puncture cell membranes |
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What is desiccation? |
Method of inhibiting microbial growth by removing liquid water to inhibit spread of most pathogens |
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What is lyophilization? |
Method of freeze drying to preserve microbes & cells using liquid nitrogen |
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How does filtration prevent microbial contamination? |
Filter pores that are small enough can trap pathogenic microbes & viruses |
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What is ionizing radiation? |
Radiation wavelengths that have sufficient energy to eject electrons from molecules they strike creating ions |
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What is nonionizing radiation? |
Radiation wavelengths that DO NOT have sufficient energy to eject electrons from molecules they strike |
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How does radiation kill microorganisms? |
Radiation denatures molecules--esp. DNA--causing fatal mutations & cell death |
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What is the mode of action for alcohols? |
--Denatures proteins (w/ H2O) --Disrupts cytoplasmic membranes |
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What is the mode of action for aldehydes? |
--Denature proteins --Inactivate nucleic acids |
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What is the mode of action for halogens? |
Denature essential proteins, including enzymes |
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What is the mode of action for heavy metals? |
Inhibit bacterial reproduction |
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What is the mode of action for oxidizing agents? |
Release oxygen radicals [NOTE: esp. effective against anaerobic microbes] |
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What is the mode of action for phenols & phenolics? |
--Denature proteins --Disrupt cell membranes |
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What is the mode of action for surfactants? |
Reduce surface tension of H2O making it more effective at dissolving solute molecules |
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What are quaternary ammonium compounds (quats)? |
Cationic detergents that disrupt cell membranes due to hydrophilic/-phobic ends |
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What is an antimicrobial agent? |
Drugs for treating infections |
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What is an antibiotic? |
Antimicrobial agents that are produced naturally by an organism |
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What is the concept of selective toxicity as it applies to antimicrobial action? |
To be effective, antimicrobials must be more toxic to a pathogen than to the host |
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What are the common modes of action for antimicrobials? |
--Inhibit cell wall synthesis --Disrupt cytoplasmic membrane --Disrupt general genetic pathway (i.e., DNA & RNA) --Inhibit protein synthesis --Inhibit general metabolic pathways --Inhibit pathogen's interaction (e.g., attachment or recognition) with host |
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How does penicillin inhibit microbial growth? |
Inhibits NAG-NAM cross-links from forming |
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How do β-lactams inhibit microbial growth? |
Inhibit peptidoglycan formation by binding to enzymes that cross-link NAM subunits (e.g., penicillin) |
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What substance mediates β-lactam resistance & how? |
β-lacatamase cleaves the β-lactam ring |
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Why is amoxicillin combined with clavulanic acid? |
Clavulanic acid is a β-lactamase inhibitor, so it prevents bacteria from cleaving the β-lactam ring |
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What is bacitracin? Describe its mode of action, |
Topical antibiotic effective against Gram-positive bacteria by blocking NAG & NAM transport from cytoplasm |
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What is the mode of action for vancomycin & cycloserine? |
Blocks ALA-ALA bridges between NAM subunits in Gram-positive bacteria |
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What is the advantage & disadvantage of vancomycin & cycloserine? |
Advantage: effective against drug-resistant bacteria Disadvantage: toxic to humans |
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How do antimicrobials work by inhibiting protein synthesis? |
Slows growth or proliferation of cells by disrupting processes that lead to generation of new proteins |
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How do antimicrobials work by disrupting plasma membrane? |
Disrupt or injure the plasma membrane causing rapid depolarization of cell, disruption of protein synthesis, &/or interaction with phospholipids in membrane |
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How do antimicrobials work by inhibiting metabolic pathways? |
Target metabolic pathways that are unique to pathogens, resulting in antigen cell death & not harm to human host |
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How do antimicrobials work by inhibiting nucleic acid synthesis? |
Disrupt RNA transcription of genetic material for translation into proteins or interfere with DNA replication |
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How do antimicrobials work by inhibiting pathogen-host recognition? |
Peptide & sugar analogs to host attachment or receptor proteins attach & block viral sites of attachment |
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What are synergistic drug combinations? |
When interaction of drugs causes 1 or more drugs to increase in effect |
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What are antagonistic drug combinations? |
When interaction of drugs causes 1 or more drugs to decrease in effect |
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What are broad-spectrum antibiotics? |
Drugs that are effective against many types of pathogens |
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What are narrow-spectrum antibiotics? |
Drugs that are effective against only a few types of pathogens |
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What is a spectrum of action? |
The number of different kinds of pathogens a drug acts against |
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What does it mean for a drug to be bactericidal? |
Kills the bacteria |
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What does it mean for a drug to be bacteriostatic? |
Prevents the growth or reproduction of bacteria |
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Describe the Kirby-Bauer test |
Antimicrobial infused discs are arranged on a petri dish uniformly inoculated with pathogen in question. After incubation, the diameter of the zone of inhibition is measured to determine efficacy of antimicrobial agent(s). |
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What is a minimum inhibitory concentration (MIC)? |
Measure of potency that expresses the smallest amt. of a drug that will inhibit growth & reproduction of a pathogen |
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What is a minimum bactericidal concentration (MBC)? |
Measure of potency that expresses the smallest amt. of drug required to kill a pathogen |
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What is the advantage & disadvantage of oral administration of antimicrobial agents? |
Advantage: Simplest method (no needles, self-administered) Disadvantage: Bodily drug concentration achieved is lower, relies on patients to follow prescribed timetables |
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What is the advantage & disadvantage of intramuscular (IM) administration of antimicrobial agents? |
Advantage: Allows drug to diffuse slowly into blood vessels of muscle tissue Disadvantage: Drug concentration in blood lower than IV administration |
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What is the advantage & disadvantage of intravenous (IV) administration of antimicrobial agents? |
Advantage: Highest concentration of drug in blood Disadvantage: Drug concentration diminishes rapidly as liver & kidneys remove drug from circulation |
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Describe an allergic reaction to a antimicrobial drug |
When antimicrobial drug triggers immune response in sensitive patients |
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Describe toxicity to an antimicrobial drug |
Adverse reaction affecting kidneys, liver, nerves etc. |
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Describe the effect an antimicrobial drug may disrupt normal flora |
Drugs that disrupt normal microbiota & their antagonism against certain other pathogens may result in secondary infections |
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What is intrinsic resistance? |
Innate ability of antigen to resist an antimicrobial agent due to inherent structural or functional characteristics |
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What is acquired resistance? |
Resistance to an antimicrobial agent acquired through the transfer of genetic material among bacteria (e.g., conjugation, etc.) |
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What are the mechanisms of resistance in antimicrobial-resistant microbes? |
--Resistant cell produces enzyme that destroys or deactivates drug --Slowing or preventing entry of drug into cell --Alters target of drug so it cannot effectively bind with with target --Alter metabolic chemistry to reduce efficacy of drug --Efflux pumps may pump antimicrobial out of cell faster than drug can act --Biofilms slow diffusion of antimicrobials |
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Why is penicillin ineffective against Gram-negative cells? |
The extra layer surrounding peptidoglycan layer prevents penicillin from working on NAG-NAM cross-links |
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What is the mechanism of action for aminoglycocides? |
Antimicrobials that inhibit protein synthesis by binding to 30S subunit causing mistranslation of mRNA by ribosomes |
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What is the mechanism of action for tetracyclines? |
Antimicrobials that inhibit protein synthesis by preventing tRNA molecules with amino acids from docking with ribsomes on 30S subunit |
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What is the mechanism of action for macrolides? |
Antimicrobials that inhibit protein synthesis by binding to the 50S subunit of ribosomes, blocking protein elongation |
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What is the mechanism of action for polyenes? |
Antifungals that inhibit cell membranes by forming a pore through membrane & causing leakage of ions from cells |
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What is the mechanism of action for polymixin? |
Topical Gram-negative antimicrobial that destroys cell membrane of target cells by disrupting structure & permeability |
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What is a virus? |
Acellular infectious agent with pieces of nucleic acid (i.e., DNA or RNA) |
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Why is a virus considered acellular? |
--No cytoplasmic membrane --No cytosol or organelles --Not capable of metabolic activity on their own |
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What are the 2 main components to a virus? |
--Capsid --Envelope (only some viruses) |
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What is a capsid? |
[Virus] Protein coat surrounding nucleic acid core |
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What is the extracellular state of a virus? |
Called a virion outside the cell; consists of capsid & sometimes an envelope, which give virion protection & recognition sites with which to bind to host cell |
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What is the intracellular state of a virus? |
Once inside a host cell, the capsid is removed & the nucleic acid of the virus remains |
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What is a viral envelope? |
Phospholipid membrane that surrounds the nucleocapsid |
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What are the components of a viral envelope? |
--Phospholipid bilayer membrane --Membrane proteins (e.g., glycoproteins) --Recognition sites to bind to host cells |
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What is the mechanism of action for isoniazid? |
Synthetic, narrow spectrum antimicrobial that disrupts cell wall synthesis by inhibiting mycolic acid synthesis |
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What is the mechanism of action for azoles? |
Systemic or topical antifungals that inhibit ergosterol synthesis in fungi |
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What is the mechanism of action for chloramphenicol? |
Antimicrobial that disrupts genetic pathways by inhibiting 50S ribosomal subunit & preventing peptide bonds between amino acids |
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What are reverse transcriptionase inhibitors? |
Antivirals that target reversetranscriptionase so virus cannot replicate |
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What are the 3 basic types of viral genetic material? |
--Double-stranded DNA --Single-stranded DNA --Double-stranded RNA |
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Describe the 3 basic shapes of viruses |
--Helical: spiral shape --Polyhedral: geodesic dome shape --Complex: all other shapes |
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Describe the virus life cycle |
--Attachment to host cell --Entry of virion or its genetic material into host cell --Synthesis of new nucleic acids & viral proteins by host cell --Assembly of new virions within host cell --Release of new virions from host cell |
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What is lytic replication (of virus)? |
Virus replication resulting in cell death by lysis of host cell |
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What is lysogenic replication (of virus)? |
Virus replication cycle in which infected host cell may grow & reproduce for many generations before they lyse |
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What is a prophage? |
Inactive, dormant virus that sticks its DNA into bacterial DNA, thus infecting each of host cell's daughter cells |
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What is lysogeny? |
Viral replication by lysogenic replication |
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Describe the various methods of culturing viruses |
--Plaque assay --Living animals --Embryonated chicken eggs --(Living animal) cell cultures in Petri dish |
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What is a plaque assay? |
Method of culturing viruses in which virus is mixed with cells & then spread on plate. Results in clear areas (plaques) where phages have lysed bacteria. |
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Describe the methods of entry for animal viruses |
--Direct entry: capsid attaches & releases its genetic material thru pore in cytoplasmic membrane --Membrane fusion: viral envelope & cytoplasmic membrane fuse, releasing capsid into host cell cytoplasm --Endocytosis: virus attaches to host cell & triggers cell into endocytize the entire virus |
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What is (viral) budding? |
Mechanism for release of viruses from host cells via exocytosis |
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What is (viral) lysis? |
Mechanism for release of viruses from host cells via lysing (bursting) host cell |
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What is a temperate virus? |
Phages that replicate thru either lytic or lysogenic cycles |
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What is a virulent virus? |
Phages that only replicate thru lytic cycles |
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What is (viral) induction? |
When phage switches from lysogenic cycle to lytic cycle |
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What is a persistent infection? |
When an infection lasts a long time & is not cleared by adaptive immune response |
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What is latent infection? |
Persistent infection where virus is dormant |
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What is a prion? |
Proteinaceous infectious agent that lacks nucleic acid |
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How is a prion different than a virus? |
Lacks nucleic acids |
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How do prions propagate? |
Amino acid sequence in PrP is misfolded into prion PrP which clump together & influence nearby normal cellular to refold into prion PrP |
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Describe how diseases caused by prions affect a person |
As clumps of prion PrPs (plaques) increase, nearby neurons stop working properly & die off leaving holes (spongy appearance) in brain |
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What is a viroid? |
Potentially pathogenic circular RNA molecules that infect plants |
