PEDAGOGY

Based on our discussions with instructors from many institutions, some common goals have emerged. Instructors want a broad textbook that clearly explains concepts in a way that is interesting, accurate, concise, and up-to-date. Likewise, most instructors want students to understand the experimentation that revealed these genetic concepts. In this textbook, concepts and experimentation are woven together to provide a story that enables students to learn the important genetic concepts that they will need in their future careers, and also be able to explain the types of experiments that allowed researchers to derive such concepts. The end of the chapter contains problems sets that are categorized according to their main focus, either conceptual or experimental, although some problems contain a little of both. The problems are meant to strengthen students' abilities in a wide variety of ways:

• To bolster their understanding of genetic principles.
• To enable students to apply genetic concepts to new situations.
• To analyze scientific data.
• To organize their thoughts regarding a genetic topic
• To improve their writing skills.

Finally, since genetics is such a broad discipline ranging from the molecular to the populational levels, many instructors have told us that it is a challenge for students to see both "the forest and the trees." It is commonly mentioned that students often have trouble connecting the concepts they have learned in molecular genetics with the traits that occur at the level of a whole organism. For example, what does transcription have to do with blue eyes? To try to make this connection more meaningful, certain figure legends in each chapter, designated Genes to Traits, remind students that molecular and cellular phenomena ultimately lead to the traits that are observed in each species.

ILLUSTRATIONS

In surveying students that I teach, I often hear it said that most of their learning comes from studying the figures. Likewise, instructors frequently use the illustrations from a textbook as a central teaching tool. For these reasons, the greatest amount of effort in improving the second edition has gone into the illustrations. Every illustration of the second edition has been redrawn with four goals in mind:

• Completeness - For most figures, it should be possible to understand an experiment or genetic concept by looking at the illustration alone. Students have complained that it is difficult to understand the content of an illustration if they have to keep switching back and forth between the figure and text. In cases where an illustration shows the steps in a scientific process, the steps are described in brief statements that allow the students to understand the whole process (e.g., see Figure 12.9). Likewise, such illustrations should make it easier for instructors to explain these processes in the classroom.
  
• Clarity - The figures have been extensively reviewed by students and instructors. This has helped us to avoid drawing things that may be confusing or unclear. I hope that no one looks at an element in any figure and wonders, "What is that thing?" Aside from being unmistakably drawn, all new elements within each figure are clearly labeled.


• Consistency - Before we began to draw the figures for the second edition, we generated a style sheet that contained recurring elements that are found in many places in the book. Examples include the DNA double helix, DNA polymerase, fruit flies, etc. We agreed upon the best way(s) to draw these elements and also what colors they should be. Therefore, as students and instructors progress through this textbook, they become accustomed to the way things should look.


• Realism - An important, albeit tiring goal of this second edition has been to make each figure as realistic as possible. When drawing macroscopic elements (e.g., fruit flies, pea plants, etc.), the illustrations have been based on real images, not on cartoon-like simplifications. Our most challenging goal, and one that we feel has been the most successful in this second edition, has been the realism of our molecular drawings. Whenever possible, we have tried to draw molecular elements according to their actual structures, if such structures are known. For example, the ways we have drawn RNA polymerase, DNA polymerase, DNA helicase, and ribosomes are based on their crystal structures. When a student sees a figure in this book that illustrates an event in transcription, RNA polymerase is depicted in a way that is as realistic as possible (e.g., see Figure 12.9).

WRITING STYLE

Motivation in learning often stems from enjoyment. If someone enjoys what they're reading, they are more likely to spend longer amounts of time with it, and focus their attention more crisply. The writing style of this book is meant to be interesting, down-to-earth, and easy to follow. Each section of every chapter begins with an overview of the contents of that section, usually with a table or figure that summarizes the broad points. The section then unfolds as a story that examines how those broad points were discovered experimentally, as well as explaining many of the finer scientific details. Important terms are introduced in boldface font. These terms are also found in the glossary.

There are various ways to make a genetics book interesting and inspiring. The subject matter itself is pretty amazing, so it's not a difficult matter to build on that. In addition to describing the concepts and experiments in ways that motivate students, it is important to draw upon examples that bring the concepts to life. In a genetics book, many of these examples come from the medical realm. This book contains lots of examples of human diseases that exemplify some of the underlying principles of genetics. Students often say that they remember certain genetic concepts because they remember how defects in certain genes can cause disease. For example, defects in DNA repair genes cause a higher predisposition to develop cancer. In addition, I have tried to be even-handed in providing examples from the microbial and plant world. Finally, students are often interested in applications of genetics that impact their everyday lives. Since we hear about genetics in the news on a daily basis, it's inspiring for students to learn the underlying basis for such technologies. Chapters 18 to 21 are devoted to genetic technologies, and applications of other technologies are found throughout this textbook. By the end of their genetics course, students should come away with a greater appreciation for the impact of genetics in their lives.