1. Disease Many different organisms cause disease. This presentation will show you some organisms that cause disease and the diseases they cause.

2. Bacteria  Bacteria are believed to be the oldest, of all life forms found on earth today.  Bacteria are prokaryotes.  Bacteria do not have a nucleus.  There are two kingdoms of bacteria: –Archaebacteria –Eubacteria

3. Bacteria come in 3 different shapes:  Coccus: sphere-shaped cells  Bacillus: rod-shaped  Spirillum: shaped like coiled rods or corkscrews

4. Bacilli bacteria

5. Cocci bacteria

6. Spirilla bacteria

7. Structure of a Bacteria Cell  Most bacteria have a rigid cell wall.  Many bacteria are surrounded in a capsule. –The capsule protects the bacteria  DNA is not found in a nucleus.  Many bacteria have one or more flagella. (For movement)  Bacteria are covered with pilli. –This allows bacteria to attach to another surface.

8. Structure of bacteria

9. Identifying bacteria  A very important test used to identify bacteria is the gram stain.  This technique was developed by the Danish microbiologist Hans Christian Gram.

10. Gram Staining  In this process bacteria are put onto a slide and stained with purple dye. –Bacteria that retain the purple dye are gram positive. –Bacteria that do not keep the purple dye are gram negative. The difference in staining is due to the composition of their cell walls.

11. Gram Staining Gram negative bacteria have a protective layer covering their cell wall. This covering makes them more resistant to drugs and other chemicals that destroy bacteria cells. Antibiotics are more effective against gram-positive bacteria.

12. Gram negative gram positive Gram staining example

13. Steps of Gram-staining

14. Comparison of gram negative & gram positive bacteria

15. Nutrition in bacteria  Most bacteria are heterotrophic. They use organic compounds made by other organisms.  Many are decomposers. They obtain their nutrition from dead organisms.  Some bacteria are parasites. They live in or on another organism. (Disease causing bacteria)

16. Nutrition in bacteria  Some bacteria live in a state of mutualism. Both host and bacteria benefit from this type of association. –Example: intestinal bacteria in humans and nitrogen fixing bacteria in the roots of some plants.  Some bacteria are photosynthetic.  Some bacteria obtain energy from the oxidation of inorganic substances instead of from the sunlight. –Nitrifying bacteria: can oxidize ammonia to nitrates.

17. These are root nodules on the roots of a bean plant. The nodules contain the nitrogen fixing bacteria Rhizobium. Nitrogen fixation

18. Bacteria reproduction  Most Bacteria have a very simple way of reproducing.  They simply split in two in the process called binary fission.  They double their DNA and divide.

19. Binary Fission

20. Disease Causing Bacteria  There are many different types of disease causing bacteria. The following slides are just a few of the many examples.

21. Anthrax Bacillus anthracis Bacillus anthracis is the causative agent of anthrax. It is a Gram-positive, aerobic, spore-forming large bacillus. Spores are formed in culture, in the soil, and in the tissues and exudates of dead animals, but not in the blood or tissues of living animals. Spores remain viable in soil for decades.

22. Anthrax Cutaneous anthrax

23. The Anthrax Scare The letter that contained anthrax spores

24. The Bubonic Plague Plague is caused by Yersinia pestis and is the disease known in the middle ages as the black death. This is because it frequently leads to gangrene and blackening of various parts of the body. Capillary fragility results in hemorrhages in the skin which also result in black patches.

25. The Bubonic Plague The three documented pandemics of plague (Black Death) have been responsible for the death of hundreds of millions of people. Today, sporadic infections still occur. In the U.S., animal plague occurs in a number of western states, usually in small rodents and in carnivores which feed on these rodents.

26. The Bubonic Plague  PANDEMIC- AFFECTING A LARGE AREA, WIDESPREAD

27. The Bubonic Plague Buboes (Swollen lymph node) The Flea that carries the plague Gangrene caused by the plague

28. The Bubonic Plague Drawing of the outfit that people would wear to prevent from smelling or coming in contact with the dead.