1. Viruses

2. What is a virus? Are tiny! Can infect a bacterium. 5 billion viruses can fit into one drop of blood!! Virus can change often –This makes them hard to fight!

3. Are viruses alive? Viruses are NOT Alive –They do not grow –They do not have cells –They do not have a metabolism Viruses are LIKE living things –Viruses contain genetic material DNA or RNA Proteins –They can reproduce But only in a host cell Answer: A virus cannot reproduce on its own, but must take over a host cell and so is not considered alive.

4. How are viruses classified? By shape Type of disease caused Life cycle (for reproduction) Type of genetic material included –DNA or RNA

5. Viral Shapes Cylinders Crystals Spheres Spacecraft (only infects bacteria)

6. Can you spot some shapes ?

7. The Lytic Cycle 1. The virus finds and attaches itself to a host cell. 2. The virus enters the cell, or injects its genetic material into the cell. 3. The virus’s genes take over the cell and turns it into a virus factory. 4. The new viruses break out of the host cell, killing it.

8. Lytic Cycle

9. Lysogenic Cycle Genetic material enters the cell. Every time the cells divides, it gets a copy of the virus. When the virus becomes active it enters the Lytic cycle

10. Illness Prevention There are no cures for any virus. Antiobiotics are only for bacteria! Try not to get sick in the first place –Wash your hands! (soap, water, 20 seconds!) –Get vaccines –Don’t touch your face or mouth

11. Treating a Virus Medicine can’t KILL a virus Your immune system must kill them. Antiviral medicine stop virus from reproducing. –Gives your body time to fight the sickness Dr. would tell you to: –REST –DRINK FLUIDS