1. Prokaryotes

2. Prokaryotes The domain of Bacteria
The typical bacterium contains: cytoplasm, nuclear material, ribosomes, a cell wall, plasma membrane, pili, flagellum, and capsule.

3. Prokaryotes
lack a cell nucleus, or any other membrane-bound organelles

4. Prokaryotes One way to classify bacteria is by examining its shape.
We will examine the three basic shapes but note that others exist.

5. Three basic shapes of bacteria
Prokaryotes
Three basic shapes of bacteria
Bacilli are rod-shaped with noticeable breaks
Cocci spherically-shaped
Spirilla spiral-shaped with smooth curves

6. Bacterial Colony Morphology study of the form and structure
Prokaryotes
Bacterial Colony Morphology
study of the form and structure
Borrelia burgdorferi
Spiral/Spirilla
Lyme disease

7. Prokaryotes Form - What is the basic shape of the colony?
For example, circular, filamentous, etc.
Escherichia coli
Bacillus/Rod

8. Prokaryotes
  Elevation - What is the cross sectional shape of the colony?
Staphylococcus aureus
Coccus- round

9. Prokaryotes
In 1884 Hans Christian Gram developed a staining procedure, Gram Staining
The composition of the cell wall of bacteria vary among species.

10. Prokaryotes

11. Due to this difference bacteria can be divided into two groups;
Prokaryotes
Due to this difference bacteria can be divided into two groups;
Gram positive
Gram negative

12. Prokaryotes Gram positive
bacteria have thick peptidoglycan cell walls and retain a purple color when stained with crystal violet.
Usually less toxic

13. Prokaryotes Gram negative
bacteria have thin peptidoglycan cell walls these cells retain the red color when stained

14. Prokaryotes Gram staining involves three processes:
1.Staining with a water-soluble dye called crystal violet,
2.Decolorization,
3.Counterstaining, usually with safanin.

15. Results
Red rods gram negative
Purple circles gram positive
Review…….

16. Prokaryotes
Reagent: is a substance or compound consumed during a chemical reaction.
Crystal violet (primary stain)
Iodine solution/Gram's Iodine ( fixes crystal violet to cell wall)
Decolorizer (e.g. ethanol)
Safranin (secondary stain)
Water (preferably in a squirt bottle)

17. Prokaryotes
Decolorizer (e.g. ethanol) which dehydrates the peptidoglycan layer, shrinking and tightening it.