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exam 3
microbiology
| Term | Definition |
|---|---|
| What factor means that larger populations take longer to eliminate? | Population size |
| How does exposure time affect microbial control? | Longer exposure increases effectiveness |
| Are young or old microbes more susceptible to control agents? | Young, actively dividing microbes are more susceptible |
| How does hydration affect microbial susceptibility? | Dry cells resist control agents better |
| What effect does heat have on microbes? | Denatures proteins and destroys membranes |
| How does moist heat (autoclave) sterilize? | Uses steam under pressure |
| How does dry heat kill microbes? | Burns to ash (incineration) |
| What is the effect of refrigeration on microbes? | Slows microbial growth (bacteriostatic, not killing) |
| How does desiccation affect microbial growth? | Removes water needed for metabolism |
| How does filtration control microbes? | Physically removes them from air or liquids |
| How does ionizing radiation kill microbes? | Damages DNA (X-rays, gamma rays) |
| How does non-ionizing UV radiation affect DNA? | Causes thymine dimers |
| How do microwaves affect microbes? | Generate heat to kill microbes |
| What do phenolic compounds do? | Disrupt membranes and denature proteins |
| How do detergents work against microbes? | Break up oils and membranes (surfactants) |
| How do heavy metals affect microbes? | Inactivate proteins via ion binding |
| What are alkylating agents and their effect? | Disrupt DNA and proteins (e.g., formalin, ethylene oxide) |
| What does 'sterile' mean? | Completely free of all life forms and spores |
| What does 'sanitize' mean? | Reduce microbial count to safe levels |
| What is a disinfectant used for? | Used on inanimate objects to kill microbes |
| What is an antiseptic used for? | Used on living tissue to kill or inhibit microbes |
| What does bacteriostatic mean? | Inhibits bacterial growth |
| What does bactericidal mean? | Kills bacteria |
| What is the thermal death point (TDP)? | Lowest temperature that kills in 10 minutes |
| What is the thermal death time (TDT)? | Time to kill at a given temperature |
| What is the decimal reduction time (D-value)? | Time to reduce population by 90% at a set temperature |
| What is incineration in microbial control? | Burns organisms; total destruction |
| What are autoclaving conditions for sterilization? | 121°C, 15 psi for 15 min; sterilizes instruments |
| What are the ideal disinfectant criteria? | Broad-spectrum, non-toxic, stable, fast-acting, effective in presence of organic matter, easy to use, inexpensive |
| What is a chemotherapeutic agent? | Synthetic chemical that kills/inhibits microbes |
| What is an antibiotic? | Naturally produced substance that inhibits/kills microbes |
| What is LD₅₀? | Amount that kills 50% of subjects |
| What is ID₅₀? | Amount that infects 50% of subjects |
| What is drug potency? | Strength of the drug (how much is needed for effect) |
| What is drug efficacy? | Maximum response achievable by the drug |
| What is the therapeutic window? | Range between effective and toxic dose |
| What is MIC (Minimum Inhibitory Concentration)? | Lowest concentration that stops visible growth |
| What is MBC (Minimum Bactericidal Concentration)? | Lowest concentration that kills 99.9% of microbes |
| What is the zone of inhibition in the Kirby-Bauer Test? | Area where bacterial growth is prevented |
| Which drugs inhibit cell wall synthesis? | Penicillin, cephalosporins, bacitracin; block peptidoglycan cross-linking via PBPs |
| Which drugs disrupt microbial membranes? | Polymyxins (effective against Gram–) |
| Which drugs inhibit protein synthesis? | Tetracycline (blocks tRNA), chloramphenicol (blocks peptide bonds) |
| Which drugs inhibit nucleic acid synthesis? | Fluoroquinolones (block DNA gyrase), rifampin (blocks RNA polymerase) |
| Which drugs block metabolic pathways? | Sulfonamides (mimic PABA → inhibit folic acid synthesis) |
| What is drug synergism? | Drugs work better together (e.g., sulfonamide + trimethoprim) |
| What is drug antagonism? | One drug interferes with the other’s action |
| What is selective toxicity? | Antibiotics target features bacteria have that humans lack (e.g., cell walls, 70S ribosomes, folic acid synthesis) |
| What is broad-spectrum antibiotic? | Effective against many species; risk of disrupting normal flora |
| What is narrow-spectrum antibiotic? | Targets specific groups of bacteria |
| What are side effects of antibiotics? | Result from damage to host cell membranes or mitochondria (similar to bacterial targets) |
| What is a frank pathogen? | Always causes disease |
| What is an opportunistic pathogen? | Causes disease only when host defenses are down |
| What are exotoxins? | Secreted proteins; very potent and specific |
| What are endotoxins? | Part of Gram– outer membrane (Lipid A); cause fever/shock |
| What are cytotoxins? | Destroy cells |
| What are neurotoxins? | Affect nerves |
| What are enterotoxins? | Affect intestinal cells |
| What are hemolysins? | Lyse red blood cells |
| What are the 5 stages of infection? | 1. Incubation – no symptoms; 2. Prodromal – mild signs; 3. Illness – peak symptoms; 4. Decline – recovery begins; 5. Convalescence – restoration of health |
| What is direct transmission? | Person-to-person |
| What is indirect transmission? | Through fomite or vehicle |
| What is droplet transmission? | Short-range aerosol |
| What is airborne transmission? | Long-range aerosol |
| What is vector-borne transmission? | Living carrier (insect) |
| What is vehicle-borne transmission? | Nonliving medium (food, water) |
| What are Koch’s Postulates? | Pathogen in all cases, isolate and culture pathogen, same disease reproduced in healthy host, re-isolate pathogen from new host |
| What is an endemic disease? | Always present in a region |
| What is an epidemic? | Sudden increase in cases |
| What is a pandemic? | Global epidemic |
| What is a sporadic disease? | Occasional cases |
| What is incidence? | New cases/time period |
| What is prevalence? | Total existing cases |
| What is morbidity rate? | % of population ill |
| What is mortality rate? | % of population dead |
| What is case-fatality rate? | Deaths among diagnosed cases |
| What is bacteremia? | Bacteria in blood |
| What is septicemia? | Bacteria multiplying in blood |
| What is toxemia? | Toxins in blood |
| What is viremia? | Viruses in blood |
| What is herd immunity? | Population-level protection |
| What is isolation? | Separate sick individuals |
| What is quarantine? | Restrict exposed individuals |
| What is vaccination? | Build immunity to pathogen |
| What is common-source transmission? | Many infected from one origin |
| What is propagated transmission? | Spread person-to-person |
| What is an index case? | First identified case |
| What is descriptive epidemiology? | Who, when, where |
| What is analytical epidemiology? | Why, how |
| What is experimental epidemiology? | Controlled testing of interventions |
| What is a notifiable disease? | Must be reported to authorities |
| What do CDC & WHO do? | Track and manage outbreaks |
| What is antigenic variation? | Pathogens change surface proteins to evade immune detection |
| What is a promoter? | A specific DNA sequence where RNA polymerase binds to start transcription; the “on switch” for a gene |
| What is a restriction enzyme? | A bacterial enzyme that cuts DNA at specific sequences; used in genetic engineering |
| What is RFLP (Restriction Fragment Length Polymorphism) analysis? | A method using restriction enzymes to cut DNA, producing fragment patterns to identify genetic differences |
| What is a plasmid? | A small, circular piece of DNA separate from the chromosome that can replicate on its own; often carries antibiotic resistance genes |
| What is a silent mutation? | A change in the DNA sequence that doesn’t change the amino acid coded; protein remains the same |
| What is transformation in bacteria? | Process by which a bacterium takes up naked DNA from its environment and incorporates it into its genome |
| What is transduction in bacteria? | Transfer of bacterial DNA from one cell to another by a virus (bacteriophage) |
| What are R-plasmids? | Plasmids that carry genes for antibiotic resistance; can be passed between bacteria through conjugation |
| What is enzymatic inactivation as a resistance mechanism? | Bacteria produce enzymes that destroy or modify an antibiotic before it can act (e.g., β-lactamase breaking down penicillin) |
| What is a magic bullet in medicine? | A term coined by Paul Ehrlich for a drug that selectively targets disease-causing microbes without harming the host |
| What does deodorize mean in the context of microbial control? | The process of removing or neutralizing unpleasant odors, often a side effect of disinfection rather than a primary microbial control goal |
Created by:
lgraves1969
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