1. Chapter 19 Bacteria and Viruses
19-3 DISEASES
CAUSED BY BACTERIA AND VIRUSES

2. 19-1 Bacteria
Bacteria are prokaryotes- unicellular organisms that lack a nucleus.
Classification was the Kingdom Monera
Now, in two separate Kingdoms:
Eubacteria
Archaebacteria

3. Bacteria

4. What’s the Difference? Eubacteria- new bacteria
Example: Escherichia coli (E. coli)
Found water, land, on and in us.
Archaebacteria- ancient bacteria
Examples: Methanogens
Found in harsh environments:
thick mud, digestive tracts of animals, hot springs

5. Identifying Prokaryotes
Shape
Cocci – spherical
Bacilli – rod shaped
Spirilla - spiral

6. How do they obtain energy?
Most are heterotrophs and many are autotrophs
Types of heterotrophs: “other”
Chemoheterotrophs (chemical)
Photoheterotrophs (light)
Types of autotrophs: “self”
Photoautotrophs (surface of lakes, oceans)
Chemoautotrophs (deep ocean)

7. Growth and Reproduction
Can divide every 20 minutes!
Two ways to reproduce:
Binary fission – dividing in half
Conjugation – form bridge and exchange DNA
When conditions become unfavorable:
Spore formation – help it survive in extreme conditions, such as heat, dryness, lack of nutrients.

8. Binary fission
conjugation
Spore formation

9. Importance of bacteria
Decomposers –
Help ecosystem recycle nutrients by breaking down dead tissue
Help in sewage treatment

10. Human Uses Used in industry – clean up oil spills
Remove wastes and poisons from water
Make drugs
Used in food

11. 19-2 Viruses
Viruses are composed of a core of DNA or RNA surrounded by a protein coat (capsid)
Virus means poison

12. Virus Structures Tobacco Mosaic T4 Bacteriophage Virus Influenza Virus
RNA
Capsid
proteins
Head
Tail sheath
DNA
Tail fiber
RNA
Capsid
Surface
proteins
Membrane
envelope

13. How does a Virus work?
Proteins of virus bind to receptors on the surface of a cell.
Cell gets “tricked” into letting the viral DNA in.
Cell then transcribes and translates viral genes.
Bacteriaphage- infects bacteria

14. Viral Replication Two different processes can occur:
Lytic Cycle: viral DNA enters host, copies are made, and cell lyses (bursts).
Lysogenic Cycle: viral DNA enters host, viral genes are replicated indefinitely.
Prophage- viral DNA incorporated in cell’s DNA

15. The Lytic Cycle...

16. The Lysogenic Cycle...

17. Both Cycles...

18. Retroviruses Retrovirus- contains RNA as its genetic information
Genetic info is copied backwards from RNA to DNA.
“Retro” means “backwards”
Ex. AIDS is caused by a retrovirus (HIV)

19. Comparison…

20. 19-3 Diseases caused by Bacteria and Viruses
Disease causing agents are pathogens
Bacteria produce disease in one of two ways:
Break down cells for food
Release toxins (poisons)

21. Examples for food or toxin release
TB – tuberculosis – destroys lung tissue
Strep throat - releases toxins into blood stream

22. FLU
EBOLA
SMALL POX
COLD VIRUS

23. Diseases caused by Bacteria
Common Diseases Caused by Bacteria
Section 19-3
Diseases caused by Bacteria
Disease
Pathogen
Prevention
Tooth decay
Lyme disease
Tetanus
Tuberculosis
Salmonella food poisoning
Pneumonia
Cholera
Streptococcus mutans
Borrelia burgdorferi
Clostridium tetani
Mycobacterium tuberculosis
Salmonella enteritidis
Streptococcus pneumoniae
Vibrio cholerae
Regular dental hygiene
Protection from tick bites
Current tetanus vaccination
Vaccination
Proper food-handling practices
Maintaining good health
Clean water supplies

24. Controlling Bacteria Sterilization – using high temperatures
Disinfectants – chemical solutions
Food storage and processing – storing in fridge or cooking food

25. Preventing Bacterial Disease
Vaccine – weakened or killed pathogen
Examples – meningitis, whooping cough
Antibiotics – block the growth and reproduction of bacteria
Examples- Penicillin or tetracycline

26. Diseases caused by Viruses
Common Diseases Caused by Viruses
Section 19-3
Diseases caused by Viruses
Type of Virus
Nucleic Acid
Disease
Oncogenic viruses
Retrovirus
Adenoviruses
Herpesviruses
Poxviruses
DNA
RNA
Cancer
Cancer, AIDS
Respiratory infections
Chickenpox
Smallpox

27. Viral disease in humans
Cannot be treated with antibiotics
Vaccines
Examples – polio, measles, mumps, chicken pox, hepatitis b