Micro Lab Flashcards
what does a condenser do?
Its 2 lenses that focus the light rays
What is magnification?
the enlargement of a specimen
What is parafocal?
The ability of the microscope to stay in focus when adjusting the objective lens to a higher power.
What is parcentric?
the ability of the microscope to keep the specimen you have in focus centered each time you increase magnification
WHat is Field of view ?
area viewing through the microscope
What is Resolution?
the smallest distance two closely spaced objects can be separated and still be differentiated as two individual objects
What is empty resolution?
An increase in magnification without the required increase in resolution
What is depth of field?
3D resolution
What is coarse vs fine focus?
Coarse bring into focus and fine brings specimen into sharp focus
Are the microscopes we use parafocal?
yes
What are electron microscopes used for?
To view cellular organelles
What is a bright field microscope
LIghts up the background.
What are cultured media?
solutions that contain nutritional requirements for bacteria to survive
WHat is agar?
Solidifying agent derived from seaweed that contains complex carbohydrates but no nutrition
What is solid media used for?
To isolate mixed cultures into isolated colonies
What is an agar slant?
Agar poured in to tubes on a slant and allowed to cool
What is an agar deep?
Agar in a test tube
What is an agar plate?
Agar poured into a sterile petri dish
What is chemically defined media?
media made of an organism’s exact known nutrional requirements
WHat is complex media?
media made of complex subsances like peptines, beef and yeast extract. Exact composition is not known. sustains large # of microorganisms.
WHat is TSA?
Tryptic soy agar or broth made of general nutrient media to grow variety of bacteria
What is enriched media?
As additional additives to grow fastidious organisms. extra vitamins, additional plant or animal extract or blood
What is a fastidious organism?
organisms that do not grow well on basic, complex media
What is sterilization?
Destroying all microorganisms and spores in a medium
What is autoclaving?
common method of sterilization using pressure, high temperature and hot steam in a chamber
How is 100 ml of TSA made?
4 grams of powdered TSA was mixed with 100 ml of water in a glass bottle. It was autoclaved for 20 minutes at 121 C
What is fixation?
glueing a cell to a slide
What is a direct stain vs a negative stain
direct stain - stains the specimen, negative stain - stains the background
What is a simple stain?
stains with one dye
What is differential stain?
stains with at least three chemical reagents
What does the primary stain do?
Gives initial color to all cells
What does the decolorizer do?
removes color from Gram negative or certain cells
What does the counterstain do?
gives contrast color to primary stain
What are gram positive bacteria?
Staphylococcus aureus and epidermidis
Strepococcus pyogenes and pneumoniae
Bacillus subtilis
WHat are gram negative bacteria?
Klebsela pneumoniae, eschericha coli, Salmonella enterica, Yernisia enterocolitica
What are the reagents of a Gram stain?
Crystal violet, iodine, ethanol, safranin
WHat differentiates the gram - from +?
- have a thin peptidoglycan and + have a thick peptidoglycan
What is the most important step of the gram stain?
decolorizer; under decolorized it gives a false +; over it gives a false negative
What is the primary stain of a simple stain?
crystal violet or methylene blue
Pure culture vs mixed culture?
single org. and important in ID and classification of bacteria vs multiple orgs.
What is aseptic transfer?
sterile transfer of bacteria
What is streak plate technique?
It reduces the number of organisms in each section, allowing the different bacteria to be spread far enough a part to grow separately
What is the capsule stain?
Called Anthony’s method. The bacteria are grown in a milk broth. The crystal violet stains the proteins of the milk broth and the cell, the capsule is decolorized by the copper sulfate making a clear halo.
DO NOT HEAT FIX.
Primary stain crystal violet. Decolorize with copper sulfate
What makes capsule staining more difficult?
it is made up of polysaccharides that resist most stains.
What is endospore stain?
Called Malachite Green method. stains turns the spores green and the vegetative cell pink.
primary stain: malachite green dye then steam. decolorize with water. counterstain with safranin
What is the acid fast stain?
Ziehl-Neelsen method. Organisms that resist acid fast alcohol.
primary stain: carbol fuchsin dye then steam. Rinse with water
Decolorize: acid alcohol
Counterstain: methylene blue
Endospore bacteria
Bacilus subtilis, Bacilus anthracis, Clostridium botulinum
Capsule stain bacteria
Bacilus subtilis, Bacilus anthracis, Klebseilla pneumonia
Acid Fast stain bacteria
Mycobacterium leprae and tuberculosis
What is the starch hydrolysis test?
Tests for amylase. Bacteria is added to starch agar and incubated. Iodine is had after incubation. Pos. if halo with no color change will appear after iodine. Neg. if agar turns dark once iodine is applied.
Pos bacteria Bacilus subtilis
What is the casein hydrolysis test?
Test for caeinase. Milk agar is inoculated and incubated. Pos if clear halo, neg if no halo.
What is the gelatin hydrolysis test?
Test for gelatinase. gelatin medium is stabbed and incubated. Pos. if it turns to liquid. Neg if it stays solid. Staphylococcus aureus
What is the lipid hydrolysis test?
Test for Lipases. Tween 80 medium is inoculated and incubated. Pos if it turns pink and Neg if no color change. Mycobacterium smegmatis
Food poisoning vs food spoilage
Food poisoning-pathogens that cause disease present in food.
Food spoilage - microorganisms that cause food to be inedible
What is a serial dilution?
the number of bacteria per unit volume of the original sample
What is a dilution factor?
the degree the original sample has been diluted in each
What are colony forming units?
A single bacterial colony originated from one viable cell of the original stock
what is the df equation?
vol. of sample added divided by total volume( sample + blank)
How do you calculate CFU/ml?
CFUs(colonies counted on the plate) divided by ( vol times df from tube plated)
What are bacteriophages?
viruses that infect bacteria
What is a plaque?
A phage incubated with a host on an agar plate
What is a plague forming unit?
one phage with one bacteria
