1. VIRUSES

2. Viruses are not living organisms
Viruses do not
Grow
Have homeostasis
Metabolize
Viruses do
Infect cells and use the cell to make more viruses
Cause disease in many organisms

4. Tobacco mosaic virus (TMV)
Virology – study of viruses
First discovered in Tobacco plants in 1935
Since then many viruses have been identified.

5. The Structure Of a Virus
Viruses are composed of a core of nucleic acid
The Nucleic acid core is surrounded by a protein coat called a capsid
The Nucleic core is either made up of DNA or RNA but never both

6. RNA or DNA? Viruses with RNA Viruses with DNA
Human immunodeficiency virus (HIV)/AIDS
Influenza viruses
Rabies
Hepatitis
Some Cancers
Viruses with DNA
Warts
Chickenpox
Mononucleosis
Herpes
Smallpox
Some cancers
RNA -Bird Flu Virus

7. Virus Shapes
Helical
Rodlike with capsid proteins winding around the core in a spiral
Tobacco Mosaic Virus

8. Virus Shapes Polyhedral Has many sides
Most polyhedral capsids have 20 sides and 12 corners

9. Virus Shapes
Polyhedral capsid attached to a helical tail.

10. Viruses Enter Living Cells
Viruses enter bacterial cells by punching a hole in the cells wall and injecting its DNA

11. E. Coli and the Bacteriophage
What it looks like in real life

12. LYTIC Cycle
In the lytic cycle, the virus reproduces itself using the host cell's chemical machinery. The red spiral lines in the drawing indicate the virus's genetic material. The orange portion is the outer shell that protects it.

13. 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. Viruses in this cycle can lay dormant for many years.
HIV….AIDS

14. Mutating viruses
Viruses can mutate when they copy the genetic material
Copy something wrong
Mistake proves useful
More powerful virus (more infectious)
Viruses don’t mutate often, except…
Influenza
HIV
Flu

16. The spread of West Nile virus (1999 – 2002) – bird, horse, mosquito or human

17. AIDS Worldwide

18. There are approx. 14,000 new cases of HIV worldwide every day
Think about it…
In the US, there is better than a 1/1000 chance of contracting HIV during unprotected sex
A person can be contagious for more than 10 years before any sign of the disease is apparent
HIV becomes AIDS when the number of immune cells drops below a predetermined number
No one dies from HIV or AIDS; people die from secondary infections (ranging from the common cold to cancer)
More than 3 million people (size of Chicago) die each year
There are approx. 14,000 new cases of HIV worldwide every day

19. How Is HIV Spread? Sexual contact Sharing contaminated needles
Blood transfusions
Breast feeding (mother to baby)
Mother to baby during pregnancy or birth

20. Vaccines
Vaccine - A weakened version of the virus that a body can beat.
Chicken Pox
Small Pox
Measles
Mumps
Biological Warfare????

21. Viruses and Cancer Cancer- uncontrolled reproduction of cells.
Can be triggered by lysogenic viruses
HPV- Human Papillomavirus – cervical cancer
Now we have a vaccine…
Could ALL cancers
be cause by viruses???