Viruses By: Spencer Lovejoy & Peter Valhouli-Farb

Viruses Viruses are not alive By themselves the can not move, grow, or reproduce Smaller then the smallest bacteria Two types of viruses Viruses have two types of Nucleic Acid In Latin, virus means “Poison”

Structure of a Virus (HIV) Glycoproteins (Receptor Site) RNA (Inside) Protein (Inside the shell) Lipid Bilayer

Reproduction Before a virus can replicate it must enter a host cell A virus recognizes and attaches to a host cell when one of its proteins interlocks with the receptor cite on the plasma membrane of the host cell. The attachment protein is found in the capsid which is inside or the envelope which is outside of the virus. Once attached to the plasma membrane of the host cell, the virus enters the cell and takes over its metabolism. Only then can the virus replicate.

Plant Viruses First plant virus recognized was the Tobacco Mosaic Virus There are more then 400 known plant viruses Cause as many as 1000 plant diseases. Some plant viruses are good for plants

Human Viruses Can be spread by: Intercourse, human fluids, lakes or ponds, germs, or can run down in the family (AIDS and HIV) Very few human viruses are deadly Human viruses can replicate in dead cells UV light can destroy a human virus or viruses

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Summary Viruses are not living Can only replicate with host cell Human and plant viruses Some viruses are deadly Consists of lipid bylayer, protein shell, and glycoproteins More than 800 known plant and human viruses