1. Bacteria & Viruses
Chapter 19

2. Bacteria Eubacteria live in harsh environments such as
are classified into the kingdoms of
live in harsh environments such as
include a variety of lifestyles such as
Bacteria
Eubacteria
Archaebacteria
Infecting large organisms
Thick mud
Living in soil
Animal digestive tracts
Salty lakes
Hot springs

3. Bacteria
Microscopic life covers nearly every square centimeter of Earth!
Bacteria are Prokaryotes (lack nucleus, small)

4. Until recently, all prokaryotes were placed in a single kingdom - Monera
Now, prokaryotes are divided into two kingdoms: eubacteria and archeobacteria

5. 1. Eubacteria: Common – live almost everywhere Very diverse
Cell Wall containing peptidoglycan
Aerobic

6. The Structure of Eubacteria
Ribosome
Cell membrane
Cell wall
Peptidoglycan
Flagellum
Pili
DNA

7. 2. Archaeobacteria No peptidoglycan
Live in harsh, oxygen free environments
Examples: thick mud, animal digestive tracts, hotsprings, salty lakes

8. Identifying Prokaryotes
Shape:
Rod – bacillus
Spherical – coccus
Spiral - spirilla

9. Bacteria Metabolism
Heterotrophs – take in organic molecules example: Staphylocccus aureus

10. Autotrophs – Photosynthesizing: Example: fresh and salt water cyanobacteria

11. Growth and Reproduction
1. Binary Fission – DNA replication, cell divides in half. Asexual

12. Growth and Reproduction
2. Conjugation – Transfer of genetic information between 2 bacterial cells
Sexual

13. Growth and Reproduction
3. Spore Formation – Bacteria form endopores when conditions are unfavorable
Remain dormant until conditions improve, then germinate.
This way bacteria can survive harsh conditions such as extreme heat, dryness, lack of nutrients

14. Importance of Bacteria
1. Decomposers – Return nutrients to the soil after being taken up by plants & animals
Sewage treatment

15. Importance of Bacteria
2. Nitrogen fixers – Convert nitrogen in soil to a form plants can use to produce amino acids
Fertilizers contain nitrogen

16. Importance of Bacteria
3. Human uses
Cleaning up oil spills
Removing waste products from water
Genetic engineering
Our intestines – E. coli
Foods

17. Louis Pasteur Major contribution to medicine:
1. Created “Germ theory” – idea that bacteria cause some disease.
2. Creating hospital practices to minimize the spread of disease
3. Creating immunization using weakened forms of microbes
4. Determinined Rabies is transmitted by viruses.
5. Pasteurization - microbes in perishable food products are destroyed using heat.

18. Diseases Caused by Bacteria
Bacteria cause disease in 2 ways:
1. Breaking down cells for food.
2. Releasing toxins that travel throughout the body.

19. Examples: Lyme disease, Tetanus, Tuberculosis, Diphtheria, Bacterial Meningitis, Strep throat, Tooth decay, Salmonella

20. Preventing Bacterial Disease
Vaccine – weakened or killed pathogens injected into the body
Body produces antibodies to prevent the disease in the future

21. Antibiotics – compounds that block the growth and reproduction of bacteria

22. Controlling Bacteria Sterilization – heat kills bacteria
Disinfectants – chemical solutions that kill pathogenic bacteria
Refrigeration – slows bacterial reproduction

23. Viruses A virus is not alive!!!!
It can replicate only by infecting living cells.
It’s made up of DNA or RNA surrounded by a protein coat.
Head - Protein
coat, (capsid)
DNA
Tail sheath
Tail fiber

24. Viral Reproduction (Infection)
Virus binds to surface of a cell and deposits DNA inside.
Cell transcribes and translates viral DNA making copies of the virus
Host cell is destroyed

25. Viruses vs. Living Cells

26. Examples of Viral Diseases
Common cold, Influenza, Small pox, Warts, AIDS, Chickenpox, Measles, Hepatitis, West Nile, Polio