1. VIRUSES By: Kurt Dawiec Class: 717 Date: January 28 th, 2010

2. What is a virus?  A VIRUS:  Can reproduce  Is nonliving  Does not have organelles  Does not grow  Does not take in food or make waste  Is a piece of nucleic acid covered with a protein (this protein is called a capsid)

3. What is a virus?  A VIRUS:  Needs the help of living things.  A virus is a parasite.  PARASITE - an organism that survives by existing on or in a host organism

4. How big is a virus?  http://learn.genetics.utah.edu/conten t/begin/cells/scale/ http://learn.genetics.utah.edu/conten t/begin/cells/scale/

5. How does a virus reproduce?  http://www.tvdsb.on.ca/westmin/scie nce/sbi3a1/Bacvirus/Virusrep.htm http://www.tvdsb.on.ca/westmin/scie nce/sbi3a1/Bacvirus/Virusrep.htm

6. A bacteriophage virus: Bacteriophage – virus that infects bacteria

7. How does a virus reproduce?  5 Steps:  1 – Virus attaches to a cell  2 – Injects genetic material into the cell

8. How does a virus reproduce?  3 – Genetic material directs the cell to make more virus parts 4 – The parts form new viruses

9. How does a virus reproduce?  5 – The cell membrane bursts, releasing new viruses

10. How does a virus reproduce?  http://www.tvdsb.on.ca/westmin/scie nce/sbi3a1/Bacvirus/Virusrep.htm http://www.tvdsb.on.ca/westmin/scie nce/sbi3a1/Bacvirus/Virusrep.htm

11. How does a virus reproduce?  A virus can be inside a living thing and remain inactive  Ex: cold sore  The cell is not always destroyed when viruses leave the cell.  Ex: HIV

13. How do we classify viruses?  Viruses are NOT in the five kingdom system  Scientists used to classify viruses based on the host (Ex: plant virus, animal virus)  Today viruses are classified by their shape and structure

14. How do we classify viruses?  3 characteristics used to classify viruses:  1 – Structure of capsid  2 – Type of nucleic acid (DNA or RNA?)  3 – The way the virus reproduces  Usually the common name of a virus is based on the disease that it causes  Example: Swine flu virus, Rabies virus

15. Head Tail Capsid Tail Fibers