2.  They are microscopic, nonliving particles  Some are harmless, while others kill their hosts, ALL are infectious!  They do not display most of the characteristics of living things  They cannot fit into any of the 6 Kingdoms  They require a host (living cell)  Once inside a living cell, then it “reproduces”

3.  These are living cells in which viruses “reproduce” or make multiples of itself  Viruses are selective with regards to their host  Viruses are packages of genetic instructions wrapped in protein  They enter only specific hosts or cell types eg. HIV only effects CD4 T cells

4.  Another common GROUP of viruses are bacteriophages: a virus that only infects bacterial cells.  It does not enter the host cell, but rather injects its DNA inside and the protein capsule remains outside the cell.

5.  Viruses vary in individual structure, but all viruses are made up of two components:  Nucleic acid : DNA or RNA  Capsid: a protein coat that gives viruses their shape and accounts for 95% of the virus; this also determines what type of cell the virus attaches to

6.  Viruses are classified into orders, families, genus and species  They are classified based on: size, shape/structure and type of genetic material

7.  They are microscopic and can only be seen using an electron microscope  They range in size between 20-40nm  **1 nm = 1.0 x 10 -6 mm

8.  They have two basic shapes:  Helical (rod-shaped)  Cubic or polyhedral (many-sided)

9.  Some viruses may have additional structures:  Envelopes: consist of lipids and are found only in some viruses; it is believed to come from the host cell when the virus exits the cell  Tail: viruses that infect bacteria have a tail used for attachment Refer to diagrams

13.  There are two ways that viruses can reproduce within a living cell:  Lytic Cycle  Lysogenic Cycle  Refer to pg 55 Figure 2.3

14.  Read pg 56 -57 make notes  Do Pg 58 #3, 5, 6, 11