Introduction

Viruses are organisms that straddle the threshold between living and nonliving things. They lack several of the essential features of all life-forms and reproduce by taking over the genetic machinery of host cells. The release of viruses from host cells results in: the spread of many infectious diseases in both plants and animals.

Chapter Outline

Structure and Classification

Studying Viruses
Structure
Classification

Reproduction and Evolution

The Lytic Cycle
The Lsogenic Cycle
Evolution

Chapter Concept

As you read, look for ways in which the structure and reproduction of viruses make them highly effective agents of infection.