Microbiology 3

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What is the most common light microscope?

Bright-field
What is contrast?

Reflects the number of visible shades in a specimen
What is resolution?

Determines how much detail can be seen
What is resolving power?

Minimum distance between 2 objects, where objects still appear as separate objects.
What is magnification?

How much larger something appears.
What is a differential stain?
- Used to distinguish to bacterial groups from each other.
- Example: Gram Stain, Acid-Fast Stain
What are the steps in a gram stain?
- Apply primary stain - Crystal Violet
- Apply mordent - Iodine
- Apply decolorizer - Usually Alcohol
- Apply counter stain - Safarin
In a gram stain, what color are the bacteria?
- Gram positive - purple
- Gram negative - red or pink
What shape is coccus?

spherical
What shape is bacillus?

Rod shaped
What shape is spirillum?

Spiral shaped
What shape is spirochete?

Helical
What is the cytoplasmic membrane?

lipid bilayer with imbedded protiens.
What is a bacterial cell wall?
- Rigid structure that gives the cell its shape.
- Distinguished gram positive/negative
What is peptidoglycan (PTG) ?

Compound found only in bacteria
What are the characteristics of a gram positive cell wall?

Thick layer of PTG
What are the characteristics of a gram negative cell wall?

Thin layer of PTG surrounded by a lipid bilayer made of lipopolysaccharides.
How does penicllin work?
- Interferes with the synthesis of PTG in the cell wall.
- More effective against Gram positive bacteria.
How does Lysozyme work?

Destoys the cell wall.
How do the differences in the cell walls effect staining of bacteria?
- Gram positive retains crystal violet complex.
- Gram negative loses crystal violet complex.

Author

kelleeeh

19940

Card Set

Microbiology 3

Description

Microbiology - A Human Perspective - Chapter 3

Updated

2010-05-19T19:23:21Z

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