1. Did you wash your hands today?
Viruses
Did you wash your hands today?

2. NOT LIVING – Not a cell (no membrane)
Virus – What is it?
NOT LIVING – Not a cell (no membrane)
Particles of genetic material in a protein
coat.
(Either DNA or RNA inside a CAPSID.)
One thing in common: They must enter a living cell and use its functions to make more viruses.

3. Several Shapes
Influenza
Hepatitus B Virus
Rabies Virus
HIV

4. Bacteriophage (bacteria attacker)
Looks like a weird spider
Example
T4 Bacteriophage

5. Growth & Reproduction Cannot grow or make proteins by itself
Must infect a host cell (Parasitic)
Can reproduce by:
Lytic Cycle
Lysogenic Cycle

6. Lytic Cycle (causes cell to burst)
The virus injects its DNA into a cell, and the cell makes copies of it.
The cell uses proteins and viral DNA to make new viruses.
The crowded cell bursts and new viruses are released.

7. Lysogenic Cycle
A piece of viral DNA is inserted into the cell DNA and becomes part of it. When the cell DNA is copied, so is the viral DNA.
The inserted viral DNA is called a PROPHAGE.
The prophage may remain inactive a long time. When it activates new viruses are made and a lytic cycle begins.

8. Body Defenses & Treatments
Skin…that’s it!
Treatments
Vaccines can prevent disease but not necessarily infection

9. Antibiotics Vs. Vaccine
Antibiotics work against bacteria, but not viruses.
Best defense against a virus is a vaccine.
Example is the cold and flu (both are viruses)

10. Vaccines How do they work…
1. Weakened or killed pathogen is injected into the patient
2. The body’s defense system makes
antibodies to fight the pathogen
3. The antibodies bind to the pathogen to
neutralize it
4. Memory cells are produced to remember
the pathogen if it infects again later and
neutralize it again.