1. Biology 11
Viruses

2. On the fringe of classification…
I am not a cell
I have no nucleus
I can reproduce if the conditions are right
I have no metabolism
What am I?

3. Virus Video:

4. Living and not living: Living because: Can reproduce
Resemble first forms of life on earth
Have evolved
Have nucleic acid (DNA, RNA)
Movement
Can mutate and change

5. Living and not living: Not-living because: Not cellular No organelles
No metabolism
No cell membrane or
cell wall

6. Anatomy:
Made of genetic material (blue print) surrounded by a protein coat
Shapes of viruses vary greatly (spherical, rod-like, cubical, many sided)
Example of a virus structure 

7. Reproduction: Do not grow Must invade a living cell!
Can reproduce but only with the help of a host cell (living cell)
Viruses are specific and only invade certain types of cells

8. Stages of reproduction/life cycle:
Absorption: virus attaches to host cell
Entry: virus injects genetic material into the cell
Replication: host cell will produce new virus parts instead of doing its normal work
Assembly: new viruses are put together and completed
Release: host cell breaks open, new viruses then attach to other cells in the area and the process starts again

10. Lytic verse Lysogenic:
Lytic: a virus life cycle during which a virus takes over a host cell, makes copies of itself and then destroys the host cell
Lysogenic: the virus does NOT destroy the host cell. The virus permanently inserts its DNA into the host cell DNA and stays there

11. Bacteriophage:
Is a type of virus that commonly infects bacteria cells.

12. Characteristics used to classify viruses:
1. Type of nucleic acid: viruses have either single-strand RNA or double-strand DNA, but never both.
2. Physical shape: Viruses are found in several general shapes
3. Envelope : whether or not they have an outer membrane (Gram + or Gram -)
4. Type of host cell: most viruses are very specific about the type of cell they invade. There are specific sites called receptor sites that the viruses attach to on the host cell's surface

14. Things that viruses cause:
Common cold
Flu
German measles
Mumps
Chicken Pox
Small Pox
Cold Sores
Herpes
Chicken pox
Hepatitis
Aids
West Nile