Practical 1 Flashcards by Emma Kolb

What does the diaphragm do on a microscope?

regulated the amount of light entering condenser

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What does the condenser do on a microscope?

concentrates light to enter objective lens

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What are the two lenses of a microscope?

ocular and objective

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How do you determine the magnification of a microscope?

10x * objective lens strength

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What is one technique to increase the resolving power?

oil immersion

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What does oil immersion do?

increase the amount of light entering the objective lens

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What type of paper do you clean objective lenses with?

lens paper

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What shape is coccus?

spherical

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What shape is bacillus?

rod-shaped

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What shape is spirillum?

spiral

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Are yeasts unicellular or multicellular?

unicellular

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Are molds unicellular or multicellular?

multicellular

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What type of bacteria are yeasts?

gram-positive

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What is the shape of yeasts?

oval shaped

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What are the four steps of the yeast wet mount?

one drop of methylene blue to slide
add one drop of yeast to dye
cover with coverslip
look under oil immersion

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What color will dead yeast stain?

blue

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What are the three types of media used in the lab?

nutrient broth
nutrient agar
tempered agar

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What is nutrient broth?

liquid medium made from peptones, beef extract and water

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What is nutrient agar?

solid medium made by adding sugar to nutrient broth

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What is tempered agar?

melted agar

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What are the three types of growth media?

broth
petri plate
slant

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Define selective media

allows growth of certain microorganisms while preventing growth of others

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Define differential media

allows some bacteria to develop differentially than others

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What are the five sterilization methods

autoclaving
dry heat sterilization
filtration
ionizing radiation
gases

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What are the directions for autoclaving?

loosen caps 121 C 15 mins

What are the three types of microbial reduction?

boiling pasteurization surface disinfection

What are the two types of aseptic techniques used in lab?

inoculating loop and inoculating needle

What does effuse growth look like?

thin and spreading

What does rhizoid growth look like?

branching

What does filiform growth look like?

dense growth

What are the three types of growth on slants?

effuse, rhizoid, filiform

What are the four types of surface growth in broth?

flocculent ring pellicle membranous

What are the four types of subsurface growth in broth?

turbid granular flocculent flaky

What are the three amounts of growth in broth?

heavy moderate slight

What is a pure culture?

contains cells belonging to the same species

What type of culturing method is used to obtain pure cultures?

streak plates

What type of aseptic transfer is used to transfer isolation to slants?

inoculating needle

How does M. luteus appear?

small and yellow

How does E. coli appear?

medium sized and white

How does S. marcescens appear?

large and red

What are the four steps to creating a smear from a slant/dish?

1. place a loop full of water on slide 2. using a needle, mix in a small amount of culture 3. dry by holding above flame 4. heat fix 4-5 times

What are three the steps to creating a smear from liquid media?

1. add 1-2 drops bacteria on slide 2. dry over flame 3. heat fix 10 times

What is a simple stain?

staining only using one dye

What are the four steps to simple staining?

1. cover heat fixed slide with crystal violet for 60 seconds 2. rinse with water 3. blot dry 4. look at under oil

What is simple staining used for?

looking at shape and arrangement of structure

How do spores appear when using simple staining?

don't stain, appear empty

How do basic dyes work?

positively charged chromophore is strongly attracted to negatively charged bacterial cell

What two types of stains are basic?

direct or simple

How do acidic dyes work?

negatively charged chromophore is not attracted to negatively charged bacteria

What type of stain is acidic?

negative stains

What is the shape and arrangement of E. coli?

small short bacilli, random

What is the shape and arrangement of B. subtilis?

large bacilli, chains

Define diplococci

pair of cocci

Define streptococci

chains of cocci

Define tetracocci

group of four cocci

Define staphlococcus

grape like

What are the 6 steps of gram staining?

1. heat fix bacterial smear 2. stain with crystal violet for 60 seconds and rinse 3. cover with Lugol's iodine for 60 seconds and rinse 4. rinse with alcohol for 10 seconds and rinse 5. cover with safranin for 30 seconds and rinse 6. blot dry

What color will gram-positive bacteria be?

purple

What color will gram-negative bacteria be?

pink

Is Serratia marcescens gram positive or negative?

gram negative

Is E. coli gram negative or positive?

gram negative

Is M. luteus gram negative or positive?

positive

Do gram positive or negative cells have a thick peptidoglycan layer?

positive

Define acid fast

microorganisms ability to resist decolorization by acid alcohol after primary staining

Why is it difficult to remove the stain in acid-fast bacteria?

mycolic acid holds onto the stain

What are the three reagents in acid fast staining?

carbol fuchsin acid alcohol methylene blue

What are the six steps in acid fast staining?

1. heat fix a mixed smear of M. phlei and S. epidermidis 2. cover with carbol fusion for 10 mins and rinse 3. hold at a 45 angle and decolorize with 2-3 drops acid alcohol 4. immediately rinse 5. counterstain with methylene blue for 1 minute 6. rinse, blot dry, use oil immersion

What is negative staining?

negatively charged bacteria are mixed with an acidic dye they repel

What does negative staining look like?

deposits of dye are around the cells and the cells appear transparent

What is the advantage of negative staining?

more accurate pic of cell morphology and size

What are the three steps for negative staining?

1. place one drop of nigrosin at one end of slide and mix two drops of E. coli in 2. perform smear and air dry 3. look at under oil

What is the reagent in negative staining?

nigrosin

What are the reagents in spore staining?

hot malachite green stain safranin

What are the results of spore staining?

hot malachite green penetrates the thich spore coat spores

What are the two methods of pasteurization?

high temp short time flash evaporation

What is the formula of a dilution?

x/x+y

What is the formula for CFU/ml?

number of colonies * dilution factor

How many CFU are on a countable plate?

25-250

What color do acid fast organisms stain?

pink

Practical 1 Flashcards

(79 cards)