What Is DNA?

Lesson Plan - Get It!

Audio:

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.

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.

^{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.

Explore these bonding rules in Build a DNA Molecule provided by Genetic Science Learning, University of Utah.

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.