Biology 2e is designed to cover the scope and sequence requirements of a typical two-semester biology course for science majors. The text provides comprehensive coverage of foundational research and core biology concepts through an evolutionary lens. Biology includes rich features that engage students in scientific inquiry, highlight careers in the biological sciences, and offer everyday applications. The book also includes various types of practice and homework questions that help students understand—and apply—key concepts. The 2nd edition has been revised to incorporate clearer, more current, and more dynamic explanations, while maintaining the same organization as the first edition. Art and illustrations have been substantially improved, and the textbook features additional assessments and related resources.

By the end of this section, you will be able to do the following:

Describe the steps involved in prokaryotic gene regulation
Explain the roles of activators, inducers, and repressors in gene regulation

This scrollable interactive explores the regulation of the araBAD operon, a set of co-regulated genes that metabolize arabinose in E. coli.

This scrollable introduces the idea of a set of co-regulated genes in prokaryotes, called an operon, using the canonical lac operon as an example.

This scrollable interactive explores the regulation of the trp operon in E. coli, a
set of co-regulated genes that govern synthesis of the amino acid tryptophan.

Two French scientists describe the research they did to figure out how bacteria turn certain genes on and off. The topic is a little involved, but the animations should help you understand the process.

This pathway includes an introduction to the ways that gene expression is regulated in both prokaryotes and eukaryotes. For a deeper look at this topic, we recommend the pathway Gene Regulation from the OpenStax textbook Biology for AP® Courses.