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As the resolution increases, what happens to the resolution distance?
As resolution increases, resolution distamce decreases
what fctn does the oil serve when using oil immersion lens?
increases resolution and gives best resolution of specimen. also decreases scattering of light.
why is it important to center the object in the field of view before you change to the next higher mag?
the field of view becomes smaller as you increase mag
what are the 2 most obvious visual observations that indicate you have a contaminant?
- 1. culture is not on the streak line
- 2. culture has different morphology(looks different)
why are agar plates normally stored in the frig & not placed back in the incubator when colonies have developed?
- more colonies will grow
- to slow growth for staining purposes
- preserve the cells
what color are gram + bacteria following gram stain procedure?
what color are gram- bacteria following gram stain procedure?
what color will dead cells appear in a gram stain?
list some factors that may induce formation of spores in bacteria
- environment(toxic waste)
- shortage of nutrients
list some factors that may induce germination of spores in bacteria
- change in environment
- optimal pH
- H2O present
what is the advantage of using the spore stain for identifying spores?
- would not be able to see older spore cultures if not using spore stain
- want to see other specimens besides spores as well
are cell walls of mycobacteria hydrophilic or hydrophobic?
what techniques are used in Ziehl-Neelsen & Kinyoun acid-fast stains to overcome the difficulties of staining acid-fast bacteria?
- acid alcohol
- phenol in carbol fusion
- heat in Zeihl-Neelsen
which component in litmus milk accounts for staining of the background in anthonys capsule stain?
compare following terms & describe their chemical composition: glycocalyx, capsule, slime layer
- glycocalyx-sticky, external sheath of prokaryotic & eukaryotic cells composed of polysaccharides
- capsule-subject of interest-glycolux composed of repeating units of organic chemicals firmly attached to the cell surface
- slime layer-loose, water-soluble glycocalyx
what role do capsules play in the disease process?
repels most stain, stains around cell, protect from phagocytosis
why do you report sensitivity to an antibiotic instead of just the size of the zone of inhibition?
- zone of inhibition will increase as the concentration of antibiotic increases
- zone not solely dependent on antibiotic
what are R plasmids?what role do they play in antibiotic resistance?
- carries an R(resistant) gene
- gene involved in spread of resistance lateral transfer
describe 5 mechanisms microorganisms use to develop antibacterial resistance:
- 1. synthesizing enzymes that inactivate the drug
- 2. decrease in cell uptake or of permeability to the drug
- 3. change in number or affinity of drug receptor sites
- 4. modification of metabolic pathway that drug affects
- 5. production of pumps which remove drug before it can act
compare and contrast synergism and antagonism:
- synergism:work together
- antagonism: work against each other
describe how you would recognize antibacteria that were interacting synergistically or antagonistically:
- synergistically: larger zone of inhibition between the two
- antagonistically: decrease in zone of inhibition, and varied shape between the two
describe the simplest way to determine if UV or other treatments produced any mutants:
changes in colony morphology
give some uses for and limitations of UV in controlling microorganism
- disinfection and sterilization of surfaces and of transparent fluids and gases
- affects specific times
- long exposure times
- UV light cannot penetrate some things like lid of petri dish
- air sanitization/water purification
what is the vector for malaria?
insect-female anopheles mosquito-biological vector
with which protozoan goup are the Plasmodium species that cause malaria classified?
which Plasmodium species causes the most severe malaria infection in humans?
Plasmodium falciparum - affects RBC's - 3 day cycle
Is Candida albicans part of normal flora?
yes under right circumstances can flourish and produce pathological conditions
what groups of individuals are most susceptible to Candida infections?
diabetics, catherized pts, & those on antibiotics
describe two diseases caused by Candida albicans
- thrush-Thrush is a yeast infection of the mucous membranes of the mouth and tongue.
- Thrush appears as whitish, velvety lesions in
- the mouth and on the tongue. Underneath the whitish material, there is
- red tissue that may bleed. The lesions can slowly increase in number
- and size.If you are immunocompromised (for example, you are HIV
- positive or receiving chemotherapy), the infection can spread to other
- organs, such as the esophagus (causing pain with swallowing), or
- throughout your body, which can be deadly.
- cutaneous candidiasis-Cutaneous candidiasis is infection of the skin with candida fungus.
- Itching (may be intense)Skin lesion or rashEnlarging patchInfection of hair follicles (folliculitis) may look like pimplesLocated on the skin folds, genitals, trunk, buttocks, under the breasts, or on other skin areasMacule or papuleMay have satellite lesions (smaller lesions next to bigger ones)Skin redness or inflammation
describe the infection caused by Pneumoscystis carninii & is it highly contagious?
- pneumonia in HIV-aids patients
- form of pneumonia, caused by the yeast-like fungus Pneumocystis jirovecii.
- Pneumocystis is commonly found in the lungs of healthy people, but being a source of opportunistic infection
- it can cause a lung infection in people with a weakened immune system.
- Pneumocystis pneumonia is especially seen in people with cancer,
- HIV/AIDS and the use of medications that affect the immune system.
Not highly contagious. People with compremised immune systems are susceptible
What is valley fever?
- fungal disease that acts like the flu
- coccidioides immitis - carried by spores
- found in soil and arid environments
two useful products produced by fungi
- conserves types of foods - bread, wine, yogurt
Are most baceria killed @ 100oC(boiling H2O)?
yes most vegetative cells are killed
What are the heat resistant bacterial structures that require the temp achieved in the steam autoclave to be eliminated?
bacterial spores, endospores, protozoan cysts, viruses
what effect does pressure have on the temp @ which H2O boils?
lower pressure causes H2O to boil at a lower temp
how does elevating the volume of liquid in a container affect the time required for autoclaving?
requires more time
what is a CFU? describe how a colony forms
- Colony forming unit
- colony arises from an isolated cell that divided to form millions of bacteria from a single cell
is an isolated colony a pure culture? explain.
yes. all cells were derived from a single parent cell
why is a petri dish inverted before incubating?
to prevent moisture from the lid running onto culture and contaminating it
explain the difference between a pure and mixed culture
- pure-cells of only one species
- mixed-cells of two or more species
what does a peer reviewed article have in it?
author(s), institutions with which they are assoc. , abstract, intro with relevant background info, detailed description of research methods and materials used with data and results(graphs, tables, micrographs, electrophoresis gel photographs) and conclusions, list of references
describe compostion of endospores and discuss benefits of endospores to bacteria that have them:
- resistent to heat and chemicals
- tough outer covering
- protein hydrated cytoplasm - thick cell walls
what are the standard conditions for autoclaving
15lbs, 15minutes, 121oC
describe structure of cell wall & how influenced with staining:
why they stain + or -
- Gram +- no outer membrane
- thick layer of peptidoglycan contains teichoic acids
- teichoic acids have a neg charge
- thickness of cell wall & neg charge retains the crystal violet (purple)
- Gram - - thin layer of peptidoglycan
- 2nd bilayer membrane
- peptidoglycan makes it difficult for purple stain to stick
- large prokaryotic, O2 producint photosynthetic cyanobacteria that fix nitrogen in specific cells (heterocysts)
- cyanobacteria produce akinetes, or resting cells, which are similar to but not as resistant as the endospores of bacillus and other species
- eisier to see than other bacteria because they are much larger and green when unstained
- fix nitrogen cells
- transport reduced nitrogen to neighboring cells in exchange for glucose
- reproductive cells - resting state cells
- produce new vegetative growth
metabolic process of anabaena
describe the life cycle of malaria parasite. include the role of and in which hosts the following forms occur:sporozoites, merozoites, gametocytes, zygote
- sporozoites-transferred from mosquito - result of sexual reproduction of parasite in mosquito
- type of trophozoite
- then goes to liver cell-
- merozoites-begin to assexually produce merozoites by schizongony.
- liver fills up with merozoites-
- liver cell bursts
- merozoites infect RBC's
- another round of asexual production - schizogony (ringform - immature merozite) (schizont - large dark cell - lots of nuclei)
- RBC burst and parasites go to other RBCS to begin cycle there
- Gametocytes-differentiated merozoites into sexual to produce oocysts to produce more sporozoites to start cycle over again
compare & contrast protozoan cysts, fungal spores, and bacterial "spores"
- cysts - parent infectious form passed in feces, condensed cytoplasm resistant cell wall, not reproductive, sc dormant, survival
- fungal spore - unicellular multicellular, nutrient reserves, sexual, asexual reproduction
- bacterial spore - most resistant, resting dormant stage, internally from sporangium
hydrophobic (lipid soluble) antibiotic:
smaller or larger zone of inhibition
hydrophilic (water soluble) antibiotic:
smaller or larger zone of inhibition
small molecular weight antibiotic:
smaller or larger zone of inhibition?
large molecular weight antibiotic:
smaller or larger zone of inhibition?