New Special Topics Boxes serve to promote greater understanding of important material and fall into four different categories:

• Essential Ideas boxes reinforce and clearly explain key concepts critical to the topic of the chapter
• Medical Applications boxes provide clear links between basic molecular principles and human health
• Historical Perspectives provide the background information or experimental paths that led to the current knowledge presented in the chapter.
• Methods and Techniques boxes explain how the powerful methods of molecular biology are actually performed.

Concept and Reasoning Checks are one or two questions at the end of each chapter section which asks students to pause and assess their understanding of the material they just read. These questions require critical thinking or integration of section topics.

Key Concepts sections provide bulleted lists of important points which follow each chapter section.

Further Readings sections at the end of every chapter direct students to current review articles and fundamental research papers, providing a source of information to reinforce and elaborate on the material presented in the chapter.

The Second Edition includes a significantly expanded and updated section on chromatin remodeling, epigenetics, the RNA world, and RNAi.