Question | Answer |
What is media? | Substance to grow bacteria |
What are four basic ingredients in media? | A. Water
B. Salt/ Sodium Chloride
C. Peptones
D. Buffers
E.Solidifying agent
F Indicators
G Selective Agents
H Enrichment |
What ingredient converts liquid to a solid medium? | Augar |
Describe Selective media | Uses dyes, antibiotics and others.
Inhibts growth of certain organisms and permits growth of others.
Used for fecal, urine, sputum, bacteria normally present inhibited so pathogens, if present, can be seen.
EXAMPLE:strep augar |
Describe differential media | uses dyes, indicators and others
Gives colonies of a particular organism a distinct and easily recognizable appearance
EXAMPLE: E. Coli |
Describe Enriched media | Contains complex organic materials that certain fastidious organisms require to grow |
What are the four solutions used to do a Gram stains? | A. Crystal violet- primary stain
B. Iodine- mordant- sticks in dye
C. Acetone/alcohol- decolorizer- strips out dye
D. Safranin-counter stain |
What color is Gram positive? | Purple |
What color is Gram negative? | Red |
What do the first and second names of microbes denote? | 1st- Genus 2nd-species |
What shape are cocci? | Round |
What shape are bacilli? | Rod Shape |
What shape are spirilla? | Sprial |
Describe cell wall | Varies in composition, accounts for different stain reactors. Rigid structure, maintains shape, some protection |
Describe plasma membrane | Semi permiable- regulates passage of materials in and out of cell wall |
Describe nucleoid | Area that stores genetic material. DNA and RNA. Not a true nucleus. |
Describe a capsule | A capsule is a sticky or gummy envelope secreted by some bacteria. Protects from phagocytosis associated with virulence mucoid growth on the augar |
Describe flagella | Aids in locomotion, propels cell |
Describe spore/endospore | Thick walled oval body. Resistant to adverse conditions, such as, heat, chemicals, drying, boiling for hours and freezing for 6 months |
Define Aerobe | Will grow in presence of free oxygen |
Describe anaerobe | Can not grow in presence of free oxygen. Obtains oxygen from other oxygen containing molecules |
Describe facultative anaerobe | Sometimes=facultative, having the ability to do a thing but not usually doing it. Basically an aerobe but can grow in the absence of free oxygen |
Define obligate anaerobe | Can grow only in complete absence of free oxygen |
What pH is best for bacterial growth? | 7- tolerates narrow range 6-8 |
What is the best time to use bacterial cultures for lab studies? | 18-24 hrs 37 degrees Celsius |
What are exotoxins? | Diffuse from the bacterial cell into surrounding tissue |
What is the Gram reaction of bacteria that produce exotoxins? | Gram pos- Example- diphtheria, tetanus, gang green, botulism |
What are endotoxins? | Bound to the cell wall, released when cell distroyed |
What is the Gram reaction of bacteria that produce endotoxins? | Gram neg- Example- typhoid, cholera |