VIRUSES

• Virus- a tiny, nonliving particle that enters and then reproduces inside a living cell• Characteristics of viruses:• Not cells• Do not use energy• Do not make food or take in food• Do not produce waste• Can only multiply when inside a cell

• Host- an organism that provides a source of energy for a virus or another organism• Parasite - an organism that lives on or in a host

and causes it harm• Viruses act like parasites and almost always kill the cells

that they multiply in

VIRUS SHAPES

VIRUS SIZE

VIRUS STRUCTURE

• Viruses attach to cells using a “lock and key” method• Each virus has unique surface proteins• these proteins allow the virus to attach to certain host

cells

HOW VIRUSES MULTIPLY

1. Adsorption - virus binds to the host cell.2. Penetration - virus injects its genome into host cell.3. Viral Genome Replication - viral genome replicates using the host's cellular machinery.4. Assembly - viral components and enzymes are produced and begin to assemble.5. Maturation - viral components assemble and viruses fully develop.6. Release - newly produced viruses are expelled from the host cell.

• http://biology.about.com/od/virology/ss/Virus-Replication.htm

• http://www.news-medical.net/health/Virus-Uses.aspx