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38 terms

Microbiology lab test 1

STUDY
PLAY
Scanning Objective lens
4x
low power objective
10x
dry high-power objective
40x
oil-immersion objective
100x
Uses elctrons as a radiation source
electron microscope
uses visible light
brightfield microscope
Electron and brightfield microscope use
electromagnet condenser lens
fluorescent microscope uses
ultra violet light and stained bacteria
steps to preperation of specimens
smear on microorganisms on slide, fixing, flood with stain, washing, drying, microscope observation
Chromophore
positive ion stain
Dyes used in microbiology are salts in which the colored ion is reffered as
Dyes
basic- positive charge chromophore
acidic- negative charge chromophore
negative stains
aka acidic stain
stains the background, bacteria do not stain with electronegative stain, because both bacteria and dye are electronegative resulting in ionic repulsion.. Advantage is NO FIXING
Gram negative bacteria
red/pink
Gram positive bacteria
purple after adding counterstain
Steps to gram staining
crystal violet, iodine, alcohol, safaranin
counter stain in gram stain
basic dye
Mordant
prevent crystal violet from leaving the cell (iodine) intensifies stain
Gram stain primary stain
crystal violet
Gram stain mordant
iodine ( intensifies the stain) prevents crystal violet from leaving the cell
gram stain decolorizing agent
ethyl alcohol disrupts the lipids coat
gram stain counterstain
safranin ( positive)
Bacteria
Negative
Gram positive and negative bacteria may appear if
Bacteria stain poorly or not at all, or older cultures of gram positive bacteria give inconsistent results
crystal violet-iodine can be removed from gram negative bacteria with alcohol because
alcohol is decolorizing agent
Myobacterium
Acid fast stain is used to differentiate what bacteria
mycolic acid
prevents the entrance of most stains into acid-fast positive cells
Carbolfuschin
primary stain for acid fast stain
Test tubes
recycle and autoclaved before washing and disposing
Chemically defined medium
Medium whose exact chemical composition is known
Complex Media
Most chemoheterotrophic bacteria are grown... Media for which the exact chemical composition varies slightly from batch to batch.
Peptones
Organic carbon, energy, in the form of meat extracts and partially digested proteins.
Nutrient broth
commonly used liquid complex medium.
Nutrient agar
When agar is added it becomes a solid medium
Agar
marine red algae with unique properties that make it useful in culture media. Few microbes degrade agar so it remains solid during microbial growth. Liquifies 100 degrees C and remains liquid state until cooled 40 degrees C.
Test tube
sterilized after preperation in autoclave using steam under pressure.
Auto clave
121degrees C for 15 pounds of pressure for 15 minutes.
Simple stains
Determines the morphology, size and arrangement
Fixing
Kills microorganisms to observe, and attaches the organism to the slide while preserving structures w/ minimal distortion