1. Viral Structure

2. Viruses Tiny Nonliving The name virus is Latin for “poison.”
Can be seen only with a powerful electron microscope
Nonliving
Not made up of cells
Cannot metabolize their own energy
Can only reproduce inside a host cell (parasites)
The name virus is Latin for “poison.”

4. Viral Structure Differ widely in size and structure
Have a nucleic acid (DNA or RNA)
Surrounded by a protein coat called a capsid
Capsid proteins match the proteins on the host cell and are highly specific

5. Review Question #1
Why is a virus not considered to be alive?

6. Review Question #2
Why can most viruses infect only a few kinds of cells?