2. Viruses Non-living - does not grow, eat, release waste, or breathe. Is able to reproduce, but only when inside a host (the cell that a virus enters) 100 times smaller than bacteria

3. Virus - A nucleic acid core encased in a protein coat that can infect cells and replicate within them

5. Structure of a Virus Capsid (protein coat) Nucleic Acid (DNA) Tail Tail Fibers

7. REPRODUCTION 1. Viruses cannot reproduce on their own 2. They need a host cell to do all the work 3. It is a five step process called the Lytic Cycle that ends in the host cells death.

8. Viral Reproduction - Lytic Cycle 1. Attachment - Virus attaches to the Host cell 2. Penetration - Virus injects its RNA or DNA 3. Replication - Host cell makes many copies of the viral RNA or DNA 4. Assembly - Host cell builds new viruses 5. Lysis - New viruses breaks out of host cell -killing it – to attack other hosts

9. 1. Attachment 2. Penetration 3. Replication of DNA 4. Protein assembly - making new viral coats 5. Lysis 4 3 5 2 1

10. Attachment/Penetration

11. LYSIS

12. MOBILITY Viruses do NOT move on their own Transferred by water, air, food, human contact MOVEMENT

13. VIRAL DISEASES Pathogenic (disease causing) Flu Hepatitis C Mumps Measles Ebola Polio HIV Polio

14. How are viruses treated? Antibiotics/medicines do NOT work on viruses About the only treatment is to drink plenty of fluids and bed rest. Some medicines may improve symptoms such as aspirin for fever.

15. What are vaccines? Vaccinations (can be live, dead or weakened) Vaccinations prevent you from getting that particular virus The flu virus mutates so rapidly that vaccines are a challenge HIV virus attacks the immune system - mutates VERY rapidly - vaccine difficult