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Micro Ex1 Spicer SG

Microbiology Exam 1, Study Guide, Spicer, Bastyr

QuestionAnswer
Why don’t you use the word “microorganism” to refer to a virus? What word/s is/are used instead? A virus is "acellular" and not a living cell or microorganism. A virus cannot survive or reproduce without the organelles of a host cell.
Describe Prokaryote Cell All bacteria are prokaryotes. All prokaryotic cells are ~10 times smaller than eukaryotic cells. Structurally, prokaryotes are simple cells compared with eukaryotes, yet they are able to make quite a nice living!
Describe Eukaryote Cell cell components: Nucleus w genetic material Organelles: ER, Golgi complex, ribosomes, lysosomes, peroxisomes, mitochondria… Cell membrane: semi-permeable membrane Cytoplasm/cytosol Cell wall: not in animal cells! (plants) Flagella/cilia
Which microorganisms are prokaryotic? Eukaryotic? Bacteria are prokaryotic. Fungus, Algae, Protozoan, and Worms are Eukaryotic. Viruses are Acellular.
Describe the sequence of events an animal virus goes through to enter and replicate inside a cell. 1. Attachment (adsorption) to host cell. 2. Penetration of virion into host cell. 3. Uncoating, to allow viral nucleic acid to escape from capsid. 4. Biosynthesis of viral pieces. 5. Assembly of viral pieces makes virions. 6. Release of virus from c
Which properties distinguish a virus from a living cell? 1 Possess DNA or RNA 2 Need host for replication, no division by binary fission, mitosis, or meiosis 4 No genes or enzymes for energy, must hijack a living cell. 5 dependent upon the host cell ribosomes, enzymes, and metabolites for protein & nucleic a
What are the components of a typical virion? 1. Genome DNA or RNA 2. Capsid: protein coat of various shapes and symmetry 3. May have outer envelope of lipids and polysaccharides. 4. May have tail, sheath, and tail fibers .
Why is the gram stain useful? It separates bacteria into 3 major categories, according to the color they stain.
How does the gram stain work? Gram positive bacteria have a thick layer of peptidoglycan in their cell walls, which retains the crystal violet-iodine complex during the decolorization step. They are deep purple (as opposed to light red/pink).
What are the 3 basic types of bacterial morphology? (use the appropriate terms) -Coccus/cocci: round or spherical -Bacillus/bacilli: rectangular or rod shaped -Spirillium, Curved/spiral shaped
Which bacteria is Rod shaped? Bacillus/bacilli: rectangular or rod shaped
Which Bacteria is Round shaped? Coccus/cocci: round or spherical
Which bacteria is curved shaped? Spirilium: Curved/spiral shaped
Importance of peptidoglycan in staining? The thickness of the peptidoglycan layer of the cell defines the color of the stain of the bacteria.
Before a stain is applied to bacteria on a glass slide, what must be done, and why? Heat fix (Bunsen burner) or methanol fix to kill the organism, preserve morphology, and anchor them to the slide.
When is an acid fast stain required? Acid fast staining drives stain through waxy cell walls, using heat and acid.
For which genus of organisms is acid fast stain required? Mycobacteria
What are the 3 categories of “unique” bacteria? Rickettsias: Chlamydias Mycoplasmas
Which diseases do each Rickettsias cause? Human diseases: Rocky Mt. spotted fever, trench fever, cat scratch disease
Which diseases do each Chlamydias cause? Diseases: trachoma, conjunctivitis, urethritis (STD), pneumonia
Which diseases do each Mycoplasmas cause? Diseases: atypical pneumonia, genitourinary infections
Describe protozoa: NUnicellular, no cell walls. Larger than prokaryotes. More animal-like than plant-like; free living and motile via flagella & cilia Contain cell membranes, nuclei, organelles. Non-photosynthetic; ingest other microbes or decaying organic matter for fo
Describe Fungi: Characteristics:Diverse group: yeasts, molds, mushrooms Ubiquitous in environment Nature’s “garbage disposal” team NOT PLANTS! Not photosynthetic, no cellulose
How are fungal infections categorized? Give examples. Categorized by Mycoses: 1) Subcutaneous: more severe, involving deeper structures. 2) Systemic: deep-seated infections involving lungs, bloodstream, CNS. Usually occur in immunocompromised patients. 
What factors affect microbial growth? 1. Availability of nutrients 2. Moisture 3. Temperature 4. pH 5. Osmotic pressure & salinity 6. Oxygen requirements All of these are starting points for controlling growth.
Describe how Availability of nutrients affects microbial growth: -Nutrients are the chemicals required by the bacteria to sustain life. -Examples of nutrients: Carbon Oxygen Hydrogen Nitrogen Phosphorus Sulfur
how many elements are necessary for life? Of the 92 naturally occurring elements, 25 of them are essential to life. Not every organism needs all of them. If we can deprive a bacterium of nutrients, we can control its growth.
describe how Moisture affects microbial growth: -Water is essential for life, even microscopic life. -Biochemistry is water based (water is a universal solvent).
Can any organism survive without water? Some organisms can survive DESSICATION using endospores & cysts to go dormant, then reactivate when moisture appears. Others cannot. A dry environment will kill them.
Describe how Temperature affects microbial growth? -Optimum growth temperatures exist in a range: minimum growth temperature (below which the organism dies) and maximum growth temperature (above which it dies). -This range depends upon the enzymes used for metabolism.
Are we as humans Thermophiles, mesophiles or psychrophiles: The human body at 37 degrees Celsius is a mesophile and provides a warm home for pathogens & normal flora. External –vs.- core temperature varies, and organisms vary in their preferences of where to grow on the body.
Describe how pH affects microbial growth? -How acid or alkaline is the environment? -ACIDOPHILES prefer pH 2 to 5 (stomach). -ALKALIPHILES prefer pH 9 (intestine). -Most microbes prefer a neutral environment (pH 7 to 7.4).
Describe Osmotic pressure & salinity effect microbial growth? -Pressure is exerted on a microbial cell from the inside as well as the outside, due to solutes dissolved in solvents. -Example: salty blood, sugary saliva
Define Osmotic pressure & salinity -Osmosis refers to the movement of water through a membrane.
Describe how oxygen effects microbial growth" Some microbes need oxygen, others do not. O2 can be an environmental variable to controll the rate of growth.
What is a bacterial colony on agar composed of? A bacterial colony on an agar plate contains millions of organisms.
DIfference between Chemically defined –vs.- complex media: A chemically defined medium is made from a recipe: every ingredient is known. A complex medium is taken from a natural source: animal organs (heart, liver, brain), fish, yeast, plants. Not every ingredient is known.
Difference between Selective –vs.- differential media A selective medium contains inhibitors to discourage the growth of other organisms, while allowing the organism of interest to grow.
What is a differential medium: A differential medium allows different organisms on one plate of agar to look different from one another, a quick way of identifying organisms. Example: MacConkey agar: gram negative bacteria will produce pink colonies because they can ferment lactose.
How is sterilization accomplished? -dry heat -autoclaving (high pressure steam) -gas -chemicals (formaldehyde) -radiation (UV, gamma rays)
What are methods of disinfection? -Pasteurization: heating liquids (milk) -Chemicals: -Anti microbial agents:-”-cide” or “-cidal” refers to killing. -Germicides kill germs.
How are chemicals used as disenfectants? Disinfectants: inanimate objects Antiseptics: living tissues Sanitization: safe levels of microbes
Which physical agents can be used to inhibit microbial growth in vitro? Heat: Cold: Desiccation: Radiation: X rays & gamma rays (high energy): Ultrasonic waves: Filtration: Gaseous atmosphere: Hyperbaric Describe the physical agent Heat:
How do chemical agents work against microbes? Target & destroy cell membranes: soaps, detergents, alcohols. Destroy enzymes & structural proteins: halogens, hydrogen peroxide, heavy metal salts, formaldehyde, ethylene oxide. Attack cell walls or nucleic acids: iodine, glutaraldehyde, chlorine
What are the types of antimicrobial Chemicals: Disinfectants: inanimate objects Antiseptics: living tissues Sanitization: safe levels of microbes
Name 2 agencies (no abbreviations) devoted to public health (1 global, 1 American). World Health Organization (WHO) Centers for Disease Control & Prevention (CDC)
Give examples of a clinical sign –vs. a symptom: Pt complains of pain = symptom. Coughing = sign
How do Animal Viruses multiply? 6 steps: 1. Attachment (adsorption) to host cell. 2. Penetration of virion into host cell. 3. Uncoating, to allow viral nucleic acid to escape from capsid. 4. Biosynthesis of viral pieces. 5. Assembly of viral pieces makes virions. 6. Release of virus from c
What is a latent viral infection? Viral infection that already exists in the physiology that is waiting for the right conditions to propagate and infest the physiology.
What are the Main concerns for infectious diseases: Pathogen characteristics; Susceptibility of humans; Reservoirs of pathogens; Transmission routes.
How does microbial antagonism work in favor of normal flora? Competing for colonization sites. Competing for nutrients. Producing toxic substance.
What role do endogenous pyrogens play in host defense? Stimulates WBCs to attack invaders. Reduces available free plasma iron. Activates lymphocytes (B & T cells) for immunity.
When clinical specimens are not collected/handled/stored properly, a diagnosis can be missed. Why? (3 reasons) 1) The etiologic agent may not be found or is destroyed. 2) Overgrowth by indigenous microflora may mask the pathogen. 3) Contaminants introduced during the collection process may interfere with finding & naming the pathogen.
Why don’t you get sick every time you are exposed to (or infected by) a pathogen? 1 The pathogen is in a hostile area of the body. 2 no specific receptor sites for attachment. 3 antibacterial factors destroy the pathogen or inhibit growth. 4: Indigenous microflora occupy and use available nutrients 5 The immune system defeats patho
Give examples of Localized infection: pimple, boil, abscess
Give examples of Systemic infection: bacteremia (blood infection), tuberculosis
Give examples of Latent infection: herpes viral infections
Give examples of Secondary infection: bacterial pneumonia may follow a viral flu or cold.
What advantage do Capsule provide a bacterium? Prevents phagocytosis, Protects and assists the evolution of the bacterium, and enhances the ability of bacteria to cause disease (i.e. prevents phagocytosis). •
What advantage do Flagella provide a bacterium? Enable movement
What advantage do Pili provide a bacterium? 2 types of Pili, 1) adhere or attach to surfaces 2) enables transfer of genetic material •
What advantage do Spores provide a bacterium? Bacteria form spores when nutrient supply is low and continue to exist until nutrient supply improves. •
What advantage do Coagulase provide a bacterium? clot plasma and protect themselves from host defenses. Phagocytes, antibodies etc •
What advantage do Kinase provide a bacterium? Help dissolve clots of host and break out bacteria.
What advantage do Hemolysin provide a bacterium? lysis of red blod cells and provides a source of iron.
What advantage do Endotoxin provide a bacterium? Integral parts of cell walls of Gram negative bacteria
What are the Main concerns for infectious diseases: Pathogen characteristics; Susceptibility of humans; Reservoirs of pathogens; Transmission routes.
What is a latent viral infection? Viral infection that already exists in the physiology that is waiting for the right conditions to propagate and infest the physiology.
Describe the physical agent Heat: practical, efficient, inexpensive method of sterilization of inanimate objects/materials.
Describe the physical agent Cold: Refrigeration slows the growth, but does not kill, microbes
Describe the physical agent Desiccation: freeze-drying; also called lyophilization. Food, vaccines, medicine can be lyophilized, then reconstituted when needed. Handy for places that have no refrigeration.
Describe the physical agent Radiation: UV lamps (“germicidal” lamps) are used in newborn nurseries, operating rooms, elevators, food service rooms, and classrooms to kill microbes.
Describe the physical agent X rays & gamma rays (high energy): used to prevent food spoilage (U.S. uses gamma rays to process chicken & red meat), to sterilize surgical instruments, to prepare vaccines, and to shrink solid tumors (which could be potential sources of infection).
Describe the physical agent Ultrasonic waves: used to clean & sterilize delicate instruments. Short sound waves are passed through tanks of liquid, dislodging organic debris. The instruments are then washed, and sterilized by another method.
Describe the physical agent Filtration: filters of various pore sizes can separate (filter) cells, large viruses, bacteria from liquids or gases.
Describe the physical agent Gaseous atmosphere: lancing wounds to expose underlying organisms to oxygen. Another example: debridement of burns to remove necrotic tissue, thus preventing gangrene from anaerobic organisms.
Describe the physical agent Hyperbaric : (increased pressure) oxygen chambers can also be used.
Describe Exoenzymes:
What are virulance Factors?
First line of defense: Physical Barriers Cellular Factors Chemical Factors Microbial Antagonism
Second Line of Defense: Transferrin Fever/Pyrogens Interferons Complement, Acute phase proteins Cytokines Inflammation Phagocytosis
Third Line of defense: Immune System
Created by: bastyr41