VirusesVirusesVirusesViruses

2.32.3

I. What are viruses?A. Virus- A strand of

hereditary material (DNA) surrounded by a protein coating.1. Viruses are NOT alive!!!2. Too small to be seen with a compound microscope

I. What are viruses?B. Examples

1. Cold sores2. Measles 3. Chicken Pox4. Colds5. Flu6. AIDS

II. How Do Viruses WorkA. Viruses CANNOT survive

without a host cell.1. They use the cell to carry out the 5 life characteristics

II. How Do Viruses WorkB. Viruses can be active or

latent.1. Active viruses cause the host cells to make new viruses

a. The virus attaches to the host cell

II. How Do Viruses Workb. The virus’ heredity material (DNA) enters the cell.c. The heredity material causes the cell to make new viruses within the celld. The cell bursts and releases new viruses and the cell is destroyed

II. How Do Viruses Work 2. Latent viruses enter

the cell, but do not become active right away.3. It takes certain environmental conditions to activate the virus to start reproducing.

a. Cold Sores

III. Fighting VirusesA. Viruses can be PREVENTED

by taking a vaccine1. Smallpox was the first vaccine

a. Discovered by Edward Jenner

b. Injected small amount of cowpox virus which caused the body to prevent smallpox

III. Fighting VirusesB. Viruses CANNOT be

TREATED!!!1. Your body must produce interpherons that protect the uninfected cells in order to stop the virus

III. Fighting VirusesC. Viruses can be good!!!

1. Gene therapy- Scientists use viruses to insert “good DNA” into patients with “bad DNA” to make them better.

RECAP-What is a virus?-Why do viruses need a host

cell?-How do viruses take over the

cell?-What is the difference

between a latent virus and an active virus?

RECAP-How are viruses prevented?-How are viruses treated?-How can viruses be used for

good?