1. Viruses

2. What is a virus?
Virus: small, nonliving particle that invades and then reproduces inside a living cell
Considered nonliving because viruses are not cells. They don’t use energy to grow or respond to their surroundings
Only multiply when within a cell.

3. Host: living thing that provides a source of energy for a virus
Parasite: organisms that live on or in a host and cause harm
Viruses can infect organisms in all 6 kingdoms
Viruses are named after the disease it causes or the organism they infect

4. The Shapes and Sizes Can be in all shapes and sizes
Round, rod-shaped, bricklike, threadlike, bulletlike, robotlike
Bacteriophage: virus that infects bacteria
Vary in shape
Smaller than cells and cannot be seen with our microscopes
Smaller than bacteria cells
Show page 48 in book then page 50

6. Structure of Viruses All viruses have two parts
Outer coat that protects
Inner coat made of genetic material
Genetic material contains instructions for making new viruses
Outer coat plays important role during invasion of a host cell
Two parts like an m&m show page 50
How virus attaches to a host transparency pg 51

7. How viruses multiply After attaching it enters the cell
Takes over the cell’s functions
Directs to make more viruses
Active viruses: immediately goes to action
Makes copy after copy
Hidden viruses: becomes part of the cell and waits to become active
Transparencies of how viruses multiply pg 52 and 53

8. Caused by a virus Influenza-flu Rabies Chicken pox Polio
Measle and mumps
Thank goodness for vaccines!!

9. Review Explain why biologists consider viruses to be nonliving.
What is the basic structure of a virus?
Compare the two ways viruses can multiply.