The silent majority: RNAs that don’t make proteins

When scientists first cracked the genetic code, they expected a simple story: DNA makes RNA, and that RNA, known as messenger RNA, makes proteins. Proteins would do all the important work — building tissues, fighting infections, digesting food. But when the DNA of our genome was finally sequenced, researchers encountered a head-scratcher: The 20,000-plus genes that carry instructions for making our proteins account for less than 2 percent of our DNA. What was the rest of it good for? For years,.