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Microbiology lab
terms for microbiology lab
| Question | Answer |
|---|---|
| visible population of microorganisms living in one place | colony |
| method of culturing microorganisms in which a sterile inoculating loop is used to spread an inoculum across the surface of a solid medium in petri dishes | streak plate |
| glycocalyx composed of repeating units of organic chemicals firmly attached to the cell surface | capsule |
| In general, what effect does the presence of capsules have on the pathogenicity of bacteria? Why? | The WBC cannot phagotosize the bacteria on surface of bacteia is antigens-recognize as foreign, covers antigens, body can't recognize as foreign. |
| What role does the capsule play in the formation of plaque on your teeth? | They enable oral bacteria to colonize the teeth, where they produce acid and cause decay, food and sugar trapped in capsule, bacteria cause plaque, cause decay. |
| what is meant by binomial system of nomenclature? | two names |
| What are the parts of a scientific name? | Genus species |
| Give the rules for capitalizing and underlining (italicizing) a scientific name. | Capitalize first lette of genus, underline scientific name. |
| To what family of organic compounds does agar belong? | carbohydrate, polysaccharide |
| For what specific purpose is agar used in the micro lab? | solidify |
| What is the natural source of agar? | seaweed, red algae |
| what five pieces of information are written on a label? | your initials, your lab section, date, name of medium or test, name of organism |
| what does aseptic technique do? | avoids contamination |
| liquid medium | broth |
| Hot liquid agar can be poured into test tube to form | slant |
| growth medium | any medium that is nutrient rich |
| biochemical medium | chemicalused to test for some kind of reaction |
| culture | population of microbes |
| ubiquitious | found everywhere |
| contamination | introducing unwanted bacteria by accident into culture |
| sterile | absence of all life |
| inoculate | intentional introduction of bacteria into culture |
| incubate | grow in controlled environment |
| culturing | collecting and growing |
| pure culture | contains only one species |
| mixed culture | contains more than one species |
| eukaryotic | true nucleus, more complex, bigger, more organelles, membrane bound organelles, DNA |
| prokaryotic | no nucleus, less complex |
| magnification | the apparent increase in size of an object viewed via microscopy |
| resolving power | ability to distinguish between objects that are close together |
| compound microscope | microscope using a series of lenses for magnification |
| binocular | microscopes with two lenses |
| magnification of scanner objective | 40x |
| magnification of low power objective | 100x |
| magnification of high dry objective | 400x |
| magnification of oil immersion objective | 1000x |
| If you have an on onject in focus with one objective, it will be visible on all objectives, needing only a touch up with the fine adjustment. | parfocal |
| Objects placed in the exact center of the viewing field using one objective will still be centered after changing to another objective. | paracentric |
| rod shaped bacteria | bacillus |
| spherical bacteria | coccus |
| curved bacilli | vibrio |
| corkscrew shaped bacteria | spirillum |
| Before switching to a higher power objective, what must be th position of the specimen in the viewing field? | in the center |
| How should the iris diaphragm be positioned for the low power objective? for the oil immersion objective? | closed, partially open |
| How many times is th fine adjustment knob to be turned? Why is it wrong to turn it more than this? | once, because you may turn it up too high and hit the lens. |
| negative stain | staining technique used primarily to reveal bacterial capsules and involving application of an acidic dye which leaves specimen colorless and background stained |
| stain composed of a single dye such as crystal violet | simple stain |
| differential stain | stain using more than one dye so that different structures can be distinguished |
| what property of bacterial cell structure makes the Gram stain possible? | bacterial cell wall |
| Two reasons for heat fixing? | to kill the bacteria and to help them adhere to the slide |
| the stains of the gram stain | (primary stain) crystal violet, (mordant)iodine, (decolorizer)acetone/alcohol, (counterstain) safranin |
| color of gram positive cells | purple |
| color of gram negative cells | pink to red |
| critical step in gram staining | timing of the decolorizer |
| When opening a culture tube, what is the purpose of flaming the mouth of the tube? | to prevent other bacteria from entering tube, prevents contamination by using heat currents |
| what is the purpose of flaming the loop? | to sterilize it |
| Gram stains are not done on older cultures of bacteria, because old gram positive bacteria do not give reliable results, why? | older cells can bleach easily making them look pink instead of purple |
| in the acid fast stain a simple of differential stain? | differential stain |
| What is the purpose of the acid fast stain | it stains cells of certain baceria that cause diseases that do not readily stain with the gram stain |
| Name two important diseases caused by acid fast bacteria, write the scientific name for each | tuberculosis, leprosy, Mycobacterium tuberculosis, Mycobacterium lepral |
| bacterial cells that re metabolizing and reproducing rapidly | vegetative cells |
| what are endospores? | dormant, highly resistant cells formed in cytoplasm of bacteria and can survive environmental extremes such as desiccation, heat, and harmful chemicals |
| what is the benefit for bacteria to be able to form endospores? | let bacteria survive adverse environmental conditions, protect the DNA |
| how long can endospores survive? | indefinately |
| name two genera of endospore-forming bacteria that are medically important? | Bacillus and Clostridium |
| Name two medically important genera of bacterai that are acid fast? | Mycobacterium and Nocardia |
| Ziehl-Neelson method | use heat to force stain in |
| critical step in acid fast stain | successly forcing the primary stain inside the cells |
| the stains of the acid fast stain | (primary)carbolfuchsion, (decolorizer)acid-alcohol, (counterstain)methylene blue |
| inoculating a sterile slant in a zigzag motion | ordinary slant |
| purpose of an ordinary slant | obtain maximum growth |
| Why do ordinary stains not work on acid fast bacteria? | they have cell walls high in lipid content |
| Method used for the acid fast stain | Ziehl-Neelsen |
| the four colony shapes | punctiform, circular, irregular, rhizoid |
| the four colony margins | entire, lobate, erose, undulate |
| colony pigment | color observed with naked eye, not white, gray or off white |
| colony density | dense colonies will appear to be balck or dark brown when using dissection scope because they block the light |
| broth characteristics | turbid, pellicle, ring, sediment |
| slant characteristics | filiform, beaded, spreading |
Created by:
jennyjustis2000
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