VirusChapter 2 Lesson 1

What are the characteristics of Viruses?

Non-living Tiny Genetic material protected by a

protein coat Unable to reproduce on their own

Why are viruses considered nonliving?

Lack characteristics of living things: › are not cells› don’t use their own energy to grow or

respond to surroundings› cannot make food, take in food or produce

wastes› cannot reproduce on their own

Viral shapes

Bacteriophages

Spherical (RNA)

Crystal (stable. Polio)

Cylinder (plant)

Virus Structure Two parts: core of genetic material & a

protein coat with surface proteins

The virus surface proteins, like keys, only fit into certain host cells› Ex. HIV infects the cells of the immune

system

Viruses & the World Can cause disease

› Once recovered from a viral illness the body becomes immune

Useful› Vaccines, built from viruses, are used to

cause immunity in organisms so they cannot be made ill from a virus

› Gene therapy uses the viral mechanism for infection to deliver new genetic material to cells that need it