1. The concepts covered here can be reviewed in your lecture notes.

2. Start by reviewing features of the influenza virus virion. On a piece of paper draw a diagram of the influenza virus virion. Label on it distinctive features of the virus, including its genome, its nucleocapsid (and its symmetry), the envelope (or membrane) and the two types of protein spikes found on the membrane. Describe the genome of the influenza virus (type and number of molecules). The influenza virus carries its own polymerase. What type of polymerase is it and why does the virus need to bring it into the cell (rather than using the cell's polymerases)?

3. Influenza viruses can undergo gradual mutations and more abrupt reassortments. On a piece of paper describe:

Reassortment
Antigenic drift
Antigenic shift

4. Draw a diagram that shows how two or three influenza viruses can undergo reassortment. Use color to distinguish the different strains that are undergoing reassortment. Now that you know how influenza viruses can undergo reassortment:

Explain how new pandemic strains of influenza virus arise?
Describe how the H1N1 swine flu virus originated in 2009.
Explain why influenza vaccines are not 100% effective?

5. If you feel that you have mastered the concepts on this page, you can move to the next topic of this subunit, which explores HIV.