1. Viruses: the itty bitty stalkers of doom!

2. ARE VIRUSES ALIVE?
NO!

3. …WHY NOT?
Viruses are infectious particles that contain DNA or RNA and a protein coat called a capsid
They are not living because they DO NOT:
Grow
Reproduce on their own
Obtain or use energy
Respond to their environment

4. Structure Capsid = protein coat DNA or RNA = genetic material
Capsids can have many different shapes!

5. SO HOW DO THEY INFECT US? Viruses can be considered a “borrowed life”
They infect cells and use the cell’s machinery and parts to help them reproduce
Viruses can infect humans, animals, plants, and bacteria.

6. HOW DO VIRUSES REPRODUCE IF THEY ARE NOT ALIVE?!
The virus attaches to a host cell
The virus’s genetic material (DNA or RNA) enters the host cell
The virus’s genetic material causes the cell to make viral protein and genetic material
New viruses form inside of the host cell
New viruses are releases when the cell bursts
Viruses need a host cell to reproduce because they are NOT living!!!!

8. HOW DO VIRUSES MUTATE?
Sometimes during the process of copying the DNA or RNA of the virus, small errors occur in the copy. Most of the time, the change kills the virus and causes it to stop multiplying. However, sometimes the mutation can instead result in a changed protein that can replicate better and become more infectious
Sometimes during the process of copying the RNA or DNA of the virus, small errors (substitutions in nucleotide base pairs) occur in the copy. These errors are replicated into subsequent copies. If the change isn't fatal to the virus and causes it to stop replicating, then the virus has resulted in a mutation. If that mutation results in a changed protein that enables the virus to survive, infect or replicate better the virus will become more infectious.

9. Viruses that infect bacteria
BACTERIOPHAGES
Viruses that infect bacteria

10. VIRAL DISEASES
HIV (retrovirus)
Smallpox
Flu
Chicken Pox
Common Cold

11. VACCINES
Vaccines are weakened viruses or pathogens that help prompt the body to create the proper immune response to give an individual protection from the virus.
Why do you only get chicken pox once? 11