DNA: The Alphabet of Life Reading Comprehension Lesson

What Is DNA?

If you have watched the news lately, you have probably heard about DNA being used as evidence in crime investigations. From a tiny sample of blood or skin, lab workers can gather enough DNA to identify a person. DNA has become a powerful tool in crime solving and medicine.

DNA stands for deoxyribonucleic acid. It is the molecule that acts like a blueprint for building our bodies. Watson and Crick discovered the structure of DNA just over 50 years ago and won a Nobel Prize for their work.

DNA’s structure is actually quite simple. A DNA molecule has three basic parts: a sugar, a phosphate group, and a nitrogen base. DNA is shaped like a double helix — much like a twisted ladder. The sugar and phosphate molecules form the sides of the ladder, while the nitrogen bases form the rungs.

The Four-Letter Code

The nitrogen bases in DNA are named adenine, thymine, cytosine, and guanine. Scientists refer to them simply as A, T, C, and G. These four letters make up the entire genetic alphabet. A DNA sequence might read: ATTCGGTAGGCCTCATG — and so on for billions of letters.

DNA molecules are specially structured so they can copy themselves. This allows genetic information to be passed from one generation to the next. Every cell in your body contains the same DNA sequence, yet different cells use different parts of that code to build skin, bone, muscle, and every other tissue.

Scientists are still working to understand all the information stored in human DNA. Advances in DNA research have led to new treatments for diseases, better understanding of human history, and even the identification of ancient species. DNA truly is the alphabet that writes the story of all living things.

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