Introduction: Viruses are not considered living things. They do not grow, evolve, or use any energy. Yet, they impact life greatly. A virus is really nothing more than some genetic material (either DNA or RNA) enclosed within a protein coat. In order for a cell to become infected, the virus must inject its genetic material into it. Once inside, the viral genetics take over the cell's genetics and convince the cell to start replicating it. This makes more viruses. Most viruses are bad, but there are a few that can be useful to humans.

This diagram represents a generalize virus. Note the "landing gear" at the bottom that is used to attach itself to a cell.

Directions for this Lesson: Answer the practice questions and then watch this video to learn more about viruses.