BIOL 3340 BIOL 3340

Chapter 2 Chapter 2

MicroscopyMicroscopy

Fixation

preserves internal and external structures and fixes them in position

organisms usually killed and firmly attached to microscope slideheat fixation – routine use with procaryotes

preserves overall morphology but not internal structures

chemical fixation – used with larger, more delicate organisms protects fine cellular substructure and morphology

Light MicroscopyLight Microscopy

Dyes and Simple Staining

Dyesmake internal and external structures of cell

more visible by increasing contrast with background

have two common features

divides microorganisms into groups based on their staining propertiese.g., Gram staine.g., acid-fast stain

Gram Staining

Gram Staining

most widely used differential staining procedure

divides bacteria into two groups based on differences in cell wall structure

Acid-fast StainingAcid Fast Staining:•particularly useful for staining members of the genus Mycobacterium

e.g., Mycobacterium tuberculosis – causes tuberculosise.g., Mycobacterium leprae – causes leprosy

•high lipid content (mycolic acids) in cell walls is responsible for their staining characteristics

Gram-negative Cell Walls and Acid Fast Fast cell wall in

Chapter 3

BibliographyBibliography

http://en.wikipedia.org/wiki/Scientific_method

https://files.kennesaw.edu/faculty/jhendrix/bio3340/home.html

Lecture PowerPoints Prescott’s Lecture PowerPoints Prescott’s Principles of Microbiology-Mc Graw Principles of Microbiology-Mc Graw Hill Co.Hill Co.