Designed to give students a deep understanding of the central topics of introductory biology, E. O. Wilson’s Life on Earth is a captivating iBooks Textbook presented as a seven-unit collection. In this third unit, we explore the structure of DNA and the processes through which DNA directs cellular activity. By studying DNA—the thread that connects the past and future of life—we create a foundation for learning about genetic inheritance, evolution, and biodiversity. Each unit of the the engagingly interactive E. O. Wilson’s Life on Earth features video, photo galleries, and Multi-Touch images and illustrations that inspire students to study, enjoy, and help protect the wonders of life on Earth.