What Is DNA?

Contributor: Hannah Brooks. Lesson ID: 12206

When a builder builds a building, he or she is supplied with instructions, or blueprints. When cells are created, they follow instructions as well! Learn about these amazing molecules that build life!


Life Science

learning style
personality style
Grade Level
Middle School (6-8), High School (9-12)
Lesson Type
Dig Deeper

Lesson Plan - Get It!

  • Did you know that the structure in the image above is responsible for sustaining all life on Earth?

You have a very special molecule in every single cell in your body.

It is constantly replicating and being used to create proteins that help support cellular processes. The molecule is called, "Deoxyribose Nucleic Acid," or DNA. It is one of the most important molecules in your entire body because it instructs your cells how to function.

cellular DNA

DNA is made up of nucleotides. The structure is similar to LEGO®s connected together to make a tall tower. Each nucleotide is made up of three components: a sugar backbone, a phosphate group, and a nitrogen base.

DNA nucleotides

Image by OpenStax, via Wikimedia Commons, is licensed under the Creative Commons Attribution 4.0 International license.

Each component of the nucleotide is shown in the image above, provided by WikiMedia Commons. The sugar and phosphate group work to provide structure for the DNA molecule, while the nitrogen bases are responsible for bonding two strands of DNA. There are four nitrogen bases in DNA: Adenine, Cytosine, Guanine, and Thymine.

  • Can you find the bonds between molecules of adenine and thymine in the image above?

These are weak bonds that are able to break apart so that DNA can replicate. Adenine always bonds with thymine, and cytosine always bonds with guanine.

Practice these bonding rules in Build a DNA Molecule (this interactive does require Flash Player), provided by Genetic Science Learning, University of Utah.

  • Were you able to bond A with C?

The strict bonding rules in DNA cause the molecule to twist, taking on the traditional double helix shape.

James Watson and Francis Crick are cited as discovering DNA, but they used the work of many scientists to develop a working theory for the structure of the molecule. One notable contributor to their research was Rosalind Franklin, a female chemist who created X-ray images of DNA that helped Watson and Crick visualize the molecule. If you want to read more about the structure and discovery of DNA, check out DNA is a Structure That Encodes Biological Information, by Scitable, Nature Education.

DNA is a really important molecule because it is capable of passing genetic information from parent to offspring and holds the blueprint for cell directions. Remember that it is made up of nucleotides containing a phosphate group and sugar to provide structure to the molecule, and a base for bonding to another DNA strand.

In the Got It? section, you will explore more about the function of DNA in a cell.

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