What is DNA and how does it work?

Although we hear a lot about DNA in the news and on crime TV shows, many are unfamiliar with what it is and why it’s so important.

I’d like to change that.

From the first time I learned about DNA as a college student, I was hooked!

In this post, I want to share a little about why this molecule is so incredibly cool! (Portions from this post were taken from my self-paced online course DNA: The Alphabet of Life)

What is DNA?

The DNA directions are written in words called genes
The directions in DNA are written in discrete units called genes

DNA stands for DeoxyriboNucleic Acid and it is a biological molecule found in all living things.

Despite the incredible variety of organisms on the planet, DNA is one thing ALL living things have in common— from the tiniest, microscopic bacterium to the enormous blue whale. Mushrooms have it. Earthworms have it. Sunflowers have it. Dinosaurs had it.

But what is it, exactly?

In the simplest of terms, DNA contains the genetic instructions for making living things. These instructions are written in a special code, and this same code is used by EVERY living organism on the planet.

DNA is the Alphabet of Life

Think of DNA like the alphabet:  every book you’ve ever read was written using a code (the alphabet) made up of 26 characters (letters). By arranging those 26 letters in different ways, we get a nearly endless supply of words.

DNA is like the alphabet of life and is the code in which the instructions for making every living thing is written.  Believe it or not, this genetic code is made up of only four characters! Nearly everything about you— your height, the color of your eyes, the shape of your ears, the dimples on your face— is caused by the unique arrangement of those 4 characters in your DNA.  Pretty amazing, huh? But how does it work?

The English alphabet is made up of 26 characters (letters).  The alphabet of life (DNA) is made up of only 4 characters, known as nucleotides.

The DNA Alphabet is Grouped into Words Called Genes

Much like the letters of the English alphabet can be  grouped together in different ways to make words, the DNA alphabet is grouped into distinct units called genes. Each gene contains the directions for building a protein.

While most people know that DNA contains an organism’s genetic instructions, many do not realize that these instructions are the “recipes” for making different proteins. Many of these proteins are expressed as observable traits. For example, people with brown eyes possess a gene that carries the directions for making a specific protein that gives their eyes a brown color.  In contrast, people with blue eyes have a different form of the gene for eye color which, when expressed, produces a protein which makes their eyes appear blue *

DNA genes code for proteins responsible for a characteristic or genetic trait
A DNA gene carries the directions for making a specific protein which is responsible for producing a characteristic or trait

This is a fantastic video!

Like a Genetic Fingerprint, Your DNA is Unique

DNA is like a genetic fingerprint:  no one on earth has exactly the same DNA.  Even the DNA of identical twins is not completely identical (due to a phenomenon called epigenetics).  

DNA is transmitted from one generation to the next through reproduction.

Have you ever looked at a child and been able to see the parts they inherited from their mom and those they inherited from their dad? In my family, my sons have features that are undoubtedly from their father and others that came from me. Maybe you even see traits you’ve inherited from your parents each time you look in the mirror.  Do you have your mother’s eyes? Your father’s nose? It’s easy to see that our observable traits have been passed down from our parents. But how does it work?

Traits are encoded by the sequences of the DNA in our genes.  When a child is conceived, he receives half of his DNA from his father and half from his mother. Every child is a unique combination of genes received from both parents.

How Many Genes Does a Human Possess?

All of the genes and genetic material an organism possesses is called its genome.  

In 2003, scientists from around the world completed the Human Genome Project and were able to sequence the entire human genome.  At this time, it is estimated that the human genome contains 20,000-25,000 genes.  

In other words, DNA contains the instructions (in the form of genes) for making at least  20,000-25,000 different proteins— each of which has a role in sustaining human life.

It has been estimated that it would take someone able to type 60 words per minute for 8 hours a day approximately 50 years to type the human genome.

So how much DNA does a human contain? Watch this video to find out. I guarantee that the answer will surprise you.

How to Extract DNA at Home

This post contains affiliate links*

Did you know that you can extract DNA at home with easy-to-find materials? It’s true.

While you can extract it from any living thing, one of the favorite materials used for at-home DNA extraction is strawberries.


First, they’re easy to find. You can use fresh or frozen strawberries.

Second, strawberries are octoploid. That means that rather than having two copies of every gene (known as diploid. Humans are diploid, having received a copy of each gene from both parents), strawberries have eight copies. Therefore, strawberries contain A LOT of DNA for their size.

The following video not only walks you through how to extract DNA from strawberries, but also explains the science behind the process.

If that isn’t cool enough, you can also extract YOUR OWN DNA at home! Granted, your yields will be less than that acquired from your strawberry extraction, but it will be your very own DNA: the stuff that makes you YOU. Watch this video to learn how.

We’ve only barely scratched the surface of all there is to learn. Here are some resources if you’d like to continue learning:

Build a DNA Molecule

The Outcome of Mutation

Organisms that have had Their Genomes Sequenced

The Animated Genome

The Epigenome at a Glance

James Watson, Francis Crick, Maurice Wilkins, and Rosalind Franklin

A Brief History from Mendel to the Human Genome Project

Make Your Own Origami DNA

DNA Coloring Sheet

If you’d like to know even more about DNA, as well as the history of our understanding of how genetics works, I recommend The Gene: An Intimate History by Siddhartha Mukherjee.

To learn more about the structure of DNA, how genes are expressed within cells, and how DNA mutations can occur and lead to diseases such as sickle cell anemia, cystic fibrosis, and cancer, check out my online, self-paced course DNA:The Alphabet of Life

To learn about about gene alleles, dominant and recessive genes, and methods of inheritance (including Mendelian inheritance, sex-linked inheritance, incomplete dominance, codominance, polygenic inheritence, and the genetics of mitochondrial DNA) see my course Genetics and Heredity.

The Complete DNA and Genetics Course Bundle contains both of these courses at a discounted price.

Subscribers to my Science Simplified Newsletter get a subscriber-exclusive coupon that can be used on these courses for even more savings!

*  Scientists have determined that eye color is determined by expression of at least 2 main genes (and  possibly as many as 14 other genes).  This is an example of what is known as polygenic inheritance and is discussed in the course entitled  Genetics and Heredity

What is DNA? Why is so important and how does it function in ALL living things?  Included are videos, ideas for optional experiments for at-home DNA extraction (you can extract YOUR OWN DNA!), and lots of links with more ideas for taking your learning farther (origami DNA, DNA coloring sheets, online simulations, etc. ).

This post contains affiliate links. As an affiliate for Amazon and Home Science Tools, if you make a purchase using one of these links, I may earn a small commission but your price remains the same. I will only share links to products and companies that I personally recommend.

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