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Lab Exam

Terms in this set (53)

Presence of acid and gas
The two critaria used to determine if the bacteria fermented a specific carbohydrate
Durham tube
detection of gases; placed upside down in the purple broth
Bromcresol purple
pH indicator used in carbohydrate fermentation media
Sucrose
Disaccharide
Glucose
Monosaccharide
Mannitol
Polysaccharide
Aerobes
Bacteria that require O2 for the electron transport chain step of aerobic respiration; they do not grow in absence of oxygen; they have enzymes to protect them from toxic superoxide ions
Anaerobes
Bacteria that do not require O2 to ferment sugars to produce ATP
Aerotolerant anaerobes
Do not require O2 but but can tolerate the presence of O2
Stric/obligate anaerobes
Do not require O2 and cannot survive in presence of O2 because they lack enzymes needed to protect them from toxic superoxide ions
Facultative anaerobes
bacteria that can grow in the presence of or absence of O2
Microarophiles
Bacteria that grow in decreased O2 levels
Capneics/capnophiles
Bacteria that prefer low O2 environment because they require higher levels of carbon dioxide
Where will the strict anaerobe grow?
At the bottom in Thioglycollate media
Plaque formation on bacterial lawn indicates that
The bactriophage is specific to the host
Phage typing
Is important to discover the source of specific bacterial infection.
What does the plaque formation indicate?
The bacteriophage is undergoing lytic cycle
In Kirby Bauer Test, where are the antibiotic discs placed?
Over the lawn of a bacteria
What is the clear area around the antibiotic discs called?
Zone of inhibition; larger the zone of inhibition, more effective is the antibiotic; measured in milimeters
What type of antibiotic is effective against a wide variety of microorganism?
Broad spectrum
Tetrad
Group of cocci arranged in cluster of 4
Streptococcus arrangement
Cocci in chains
Staphylococcus arranangement
Irregular group of round bacteria with no specific arrangement
Sarcinae arrangement
Group of cocci arranged in cluster of 8
Diplobacillus
Two rod shaped bacteria attached together
Morphology
The study of cell shape and arrangment
What is the proper procedure for smear preparation?
Make smear-->air dry-->heat fix
Methylene blue and Crystal violet
Basic stains with a positively charged chromatogen
Simple staining
Requires use of a single stain
Decolorizing agent
Used in differential staining
Acidic stains
Use negatively charged chromatogens
Differential staining
Requires the use of two dyes
What is the decolorizer used to identify Mycobacterium smegmatis?
Acid alcohol
Carbol fuchsin
Primary stain in Acid-fast staining
Crystal violet
Primary stain in Gram staining
Methylene blue
Counter stain in Acid fast staining
Safranin
Counter stain in Gram staining
Nigrosin
Used in acidic stain
At the end of Gram staining
Gram positive bacteria stain purple while Gram negative bacteria stain red
What is the purpose of using decolorizing agent in Gram staining?
a. In Gram negative cells alcohol increases the porosity of cell wall by dissolving the lipid in outer layer, removing the CV-I complexes
b. In Gram positive cells alcohol dehydrates cell wall and
Why are bacteria not stained in negative staining?
Both the bacterial cell wall and the dye are negatively charged, so they repel each other
Presence of flagella
Contributes to bacterial pathogenecity
What is the concentration of agar in the motility test media?
0.3%-0.5%
What color does Tritetrazolium chloride turn in reduced form?
Red
What are the criteria used in identification of different types of colonies?
Color, elevation, texture and margins
In an isolated colony obtained from streak plate or pour plate method...
All cells are descedents of the same bacteria
what type of media is MacConkey media?
Selective and differential; promotes growtn of Gram negative bacteria while inhibiting that of Gram positive bacteria
If a bacteria grows in MacConkey media and forms red colonies, it means that the bacteria is
G- and lactose fermenter
Salt intolerant
If the growth of a bacteria is inhibited in Mannitol Salt Agar media
Mannitol Salt Agar media
7.5% NaCl
Sheep Blood Agar media
Enriched and differential media
Phenol red
pH indicator
Purpose of having sheep blood in Blood agar media is to
Detect hemolysis and provide nutrients for growth of fastedious bacteria
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