1. Viruses, Bacteria & Diseases

2. Viruses
Viruses are NOT cells. A virus is an infectious agent made up of:
a core of nucleic acid (RNA or DNA)
a protein coat (capsid)
Genetic material carries information for multiplication
Hijacks biochemical machinery of host
cell to carry these processes out
So…viruses are NOT LIVING

3. Characteristics of life
CELL
VIRUS
Made of cells
YES NO
Obtain & use energy
Grow & develop
Only inside a living cell
Reproduce
Respond & adapt
Contain RNA or DNA

4. Re-Cap Viruses are NOT ALIVE. Viruses do not: Viruses do: Grow
Have homeostasis
Metabolize
Viruses do:
Infect cells and use the cell to make more viruses
Cause disease in many organisms

5. Structure of a virus Envelope (part of the protein coat)
Capsid (part of the protein coat)
Nucleic acid (either DNA or RNA)
NUCLEIC
ACID
CAPSID

6. Retrovirus A virus that contains RNA instead of DNA
CAPSID
A virus that contains RNA instead of DNA
Human Immunodeficiency Virus (HIV) is a retrovirus
HIV causes AIDS
ENVELOPE
RNA

7. Bacteriophage A virus that only infects bacteria CAPSID HEAD DNA
TAIL FIBER

8. Ticking time bombs . . .
Viruses do not reproduce by themselves. They invade a living cell and let the cell do the work for them.

9. Lytic Cycle
The viral infection that rapidly kills the host cell is the lytic cycle.

10. Cycle Illustration 1 2 3 4 5

11. Lysogenic Cycle
The viral infection that enters a cell, remains harmless for a period of time (sometimes years), and then becomes harmful later is called the lysogenic cycle.

12. Lysogenic Cycle
In the lysogenic cycle, the virus reproduces by first injecting its genetic material, indicated by the red line, into the host cell's genetic instructions.

13. Role of viruses All viruses act like parasites, harming the host cell.
Viruses cause disease in every kind of organism—animals, plants, fungi, protists, and bacteria.

14. Some viral diseases HIV Measles Smallpox Influenza Chicken pox
Common cold
Herpes
Warts
Mononucleosis
Mumps

15. HIV
A retrovirus
Infects human helper T-cells, which are associated with the immune system.
Modes of transmission:
Sexual contact with an infected person
Sharing needles with an infected person
Blood transfusions (rare)
Breast feeding
Etc.

16. HPV Human Papilloma Virus Causes warts
Most common STD in the United States
80% of women by the age of 50 will have acquired some strain of genital HPV.
HPV vaccine

17. Influenza (flu)
Symptoms: body aches, fever, coughing, runny nose, fatigue, usually lasting about a week.
Mode of transmission
Airborne (air droplets)
People still die from influenza.

18. Viral diseases usually cannot be cured, but many can be prevented by
Good hygiene
Immunization

19. Bacteria are Prokaryotes. Prokaryotic Cells:
Have no nucleus
Do not have membrane bound organelles
Are very small
Often have a flagellum for movement

20. Shapes of bacteria Bacteria are classified according to their shape:
Round is called cocci
Rod shaped is called bacilla
Spiral shaped is called spirilla

21. Where do they live?
Bacteria are found in all environments

22. Role of bacteria Some bacteria are helpful Some bacteria are harmful
E. coli
Yeast
V.streptococci
Lactobacillus
Some bacteria are harmful
S. pyogenes
S. aureus
Y. pestis

23. Streptococcus Causes strep throat, pneumonia, and other infections.
Named based on the shape and orientation of the bacteria.

24. Staphylococcus
Cause of staph infections that occur on the skin or in wounds. (ex. MRSA)
But, Certain types of staph reside normally on the skin.

25. Diphtheria Swelling of the upper respiratory tract DPT Vaccine
Can also infect skin cells.

26. How do bacteria cause disease?
The release toxins that interfere with normal activity.

27. Prevention/Cure Vaccines to prevent.
Antibiotics to cure (pennicillin, amoxycillin, etc).