Latin for “toxic” or “poison”

A virus is a non-living microscopic particle, much smaller than a bacteria, which cannot grow or reproduce apart from a living cell. A virus invades living cells, called a host cell, and must use the host cell in order to replicate itself.

• Viruses are not affected by antibiotics.

• Viruses contain genetic information, either DNA or RNA surrounded by a protein.

• Viruses are much smaller than a bacteria.

• Viruses must have a host cell in order to replicate.

• All viruses are harmful, where as some bacteria can be beneficial to organisms.

Most viruses have NO cure (Influenza, &

HIV), but some viruses like

Small- pox have vaccines.

Vaccines contain a weakened or killed virus that provides immunity

to the disease.

Viruses are NOT cells and are not made-up of cells. They don’t…

Contain a nucleus or cytoplasm

Eat

Grow

Carry on respiration

Or perform other biological functions

A virus is surrounded by a capsid (protein coat) which determines the shape of the virus.

The capsid contains nucleic acids (either DNA or RNA).

Tail fibers

for attachment to host cell.

Disease Transmission Symptoms

AIDS/HIV Sexual contact; contaminated blood or needles

Immune system failure; fatal

CommonCold

Inhalation, direct contact

Sinus congestion, muscle aches, cough, fever

Smallpox

Inhalation Blisters, lesions, fever, blindness, scars; often fatal

Influenza(Flu)

Inhalation Headache, muscle ache, sore throat, cough, fatigue, fever, chills

Warts Direct contact Lumps on skin or mucus membranes

Virus CycleLytic and Lysogenic Cycles