
The spiral structure in the picture is a large organic molecule. Can you guess what it is? Here’s a hint: molecules like this one determine who you are. They contain genetic information that controls your characteristics. They determine your eye color, facial features, and other physical attributes. What molecule is it?
You probably answered “DNA.” Today, it is commonly known that DNA is the genetic material. For a long time, scientists knew such molecules existed. They were aware that genetic information was contained within organic molecules. However, they didn’t know which type of molecules play this role. In fact, for many decades, scientists thought that proteins were the molecules that carry genetic information. In this chapter, you will learn how scientists discovered that DNA carries the code of life.
Chapter Outline
7.4 Regulation of Gene Expression
Opening image copyright by 4designerart, 2010. http://www.shutterstock.com. Used under license from Shutterstock.com.

Licensed under
CK-12 Foundation is licensed under Creative Commons AttributionNonCommercial 3.0 Unported (CC BY-NC 3.0)”
• Terms of Use • Attribution
Changes/edits were made to the original ck12 biology text by Guest Hollow. Changes are not endorsed by ck12 in any way.