Microscopy

Resolution

Ability to distinguish between two points

How can we improve resulting on a light microscope?

Blue light (450-500 nm), oil immersion (less refraction and scattering), and aperature (bigger cone of light)

When was differential staining invented?

1884 - Christian Gram

Which cells are gram positive and which are gram negative?

Gram positive - purple

Gram negative - pink

What are the steps of Gram Staining?

1) Crystal violet - primary stain (purple)

2) Iodine - binds stain

3) Alcohol- decolonizes gram positive

4) Safranin - counterstain (pink)

What is acid fast staining used for and an example?

Mycolic acids in the cell walls (pink is positive, blue is negative)

Ex: Mycobacterium tuberculosis

What is negative staining and an example?

Capsule staining - clear capsule around bacterium

Ex: Klebsiella pneumoniae

What is endospore staining and an example?

Endospore staining - endospores stained green

Ex: Bacillus and Clostridium

How big are viruses and what can we see them with?

10-100 nm, scanning and transmission electron microscope

How big are typical bacteria?

1-5 microns

How are light and electron microscopes different?

Electron microscopes use magnets instead of lenses and a vacuum system, whereas light microscopes just use a series of glass lenses to magnify images.