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40 Cards in this Set

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Identify the parts of the microscope

Pictures in Text Book p. 48 or Lab Manual p. 125

Identify the parts of the microscope--




What is the ocular lens?


the eyepiece; the lens close to the eye; magnifies the image, usually 10-fold (10X)

Identify the parts of the microscope--




What is the objective lens?


--a series of lenses housed in a tube immediately above the object being viewed


--the selection of lens options provides different magnifications

Identify the parts of the microscope--




What is the condenser lens?


--Lens positioned between the light source and the specimen


--It does not magnify, if focuses the light on the specimen


Identify the parts of the microscope--




Iris diaphragm lever


controls the amount of light that enters the objective lens


Identify the parts of the microscope--




Rheostat


controls the brightness of the light

Calculate total magnification

Magnification is the product of the objective lens (4x, 10x, 40x and 100x) multiplied by the ocular lens (10x)




Total Magnification = ocular lens X objective lens


Example: 10X ocular lens, 100X objective lens


Total Magnification = 1000X (ocular lens X objective lens: 10 X 100)

Know the steps to proper aseptic technique
Every single growth media you inoculate should be labeled with the following:

--you or your groups name


--the name or initials of the microbe added (the inoculant)


--the type of sterile media that is present in the culture


--the date


Flame base to tip red hot (decreases aerosols)

Outcomes if aseptic technique is not done properly

1) organisms could be introduced from the outside environment and cause contamination




2) you could contaminate the environment



Morphology and Arrangements--




What is morphology?


the shape of an organism


Morphology and Arrangements--




What is arrangement?


the way bacteria stay attached to each other after cell division


Morphology--




Coccus


spherical shaped organism


Morphology--




Bacillus

--rod shaped organism


--most common

Morphology--




Vibrio


comma shaped or bent rods

Morphology--




Spirillum


loose wave like shape

Morphology--




Spirochete


spiral shaped (tight corkscrew)

Arrangements--




Diplo


arranged in pairs

Arrangements--




Strepto


long chains or strings

Arrangements--




Tetrad


groups of four

Arrangements--




Staphylo


clumps or clusters

Arrangements--




Spirillum


rarely are seen as anything other than single cells
Purpose of staining

You can tell morphology of your organism and arrangement and its size. It is fast, inexpensive, and simple.

Procedure for creating a smear

1) Write on slide


--type of bacteria


--up on one side with bacteria


--your initials


2) loop onto slide


3) air dry 10-15 minutes


4) heat fix (will kill or attach bacteria)


5) let cool about 5 minutes


6) let sit in stain for 1 minute


7) rinse for 1 minute


8) dry (sandwich it in and pat dry only)

Importance of heat fixing
It kills bacteria, attaches them to the slide

Outcomes of simple stain vs. gram stain

Simple stain: will help determine morphology and arrangement of your organism and its size




Gram stain: will determine gram-negative or gram-positive bacteria in addition to determining morphology, arrangement and size. Gram (-) cells will look red under the microscope, Gram (+) will look purple under the microscope

Proper procedure for creating a gram stain

--Crystal Violet (primary stain): all cells +/- will stain purple


--Iodine: acts as a mordant, which is a substance used to set dyes (stick together)


--Ethanol (decolorization step): Gram (-) will decolorize due to the smaller amount of peptidoglycan.


--Safranin (counterstain): both types of cells will pick up safranin which is red in color. Safranin will be masked by the crystal violet dye.


Possible outcomes if gram stain is not done properly


You will get gram variable results:


--decolorize too long is most likely source of incorrect results


--over decolorize removes CVI complex from both (+/-)


--under decolorize gram (-) cells still retain CVI complex


--too thick emulsion and you will obtain incorrect results


--aging cells lose their ability to resist decolorization

Purpose of MSA (Mannitol Salt Agar) and EMB (Eosin Methylene Blue) plates
They are selective differential media. They inhibit the growth of some organisms while encouraging or enhancing the growth of others
Know the selective and differential components of the MSA (Mannitol Salt Agar) plate?

--selective component: salt


--differential component: mannitol


Know the selective and differential components of the EMB (Eosin Methylene Blue) plate?

--selective component: the 2 dyes


--differential component: lactose or sucrose


What organism do you expect to grow/ferment/etc. on the MSA (Mannitol Salt Agar) plate?


--selects for staphylococcus bacteria


--differentiates s. aureus from all other members of the genus


What organism do you expect to grow/ferment/etc. on the EMB (Eosin Methylene Blue) plate?

gram negative organisms
Physical identification of the MSA (Mannitol Salt Agar) plate and the organism


--s. aureus will appear as bright yellow colonies usually surrounded by a yellow halo and the pH of the medium is lowered because it produces acid




--other staphylococci will appear pink or red and the medium remains unchanged

Physical identification of the EMB (Eosin Methylene Blue) plate and the organism


--vigorous fermenters will be dark purple with green metallic sheen


--moderate fermenters will appear pink


--non fermenters will be the normal color of the bacterium

Purpose of the streak plate


--isolation technique to obtain a pure culture


--all colonies will be on the surface


--streaking decreases cell density


--allows for formation of colonies

Define colony

--mound of cells growing on an agar that started as a single cell


--to produce pure culture the colony can't touch other colonies and we can't be sure it came from one single bacteria


Define pure culture
a population of cells resulting from the growth of a single cell

Define mixed culture

a culture consisting of 2 or more species of bacteria

Be able to identify mixed cultures and colonies

???

Know the significance of getting a colony

Can help identify a microorganism