DNA Lesson for Kids: Definition & Structure

Instructor: Rachel Torrens
Did you know there is a secret code contained within every one of your body's cells? Its nickname is DNA. To discover its full name and fascinating structure, read this lesson!

What Is DNA?

In P.D. Eastman's book Are You My Mother? a baby bird goes in search of his mother. He asks a cow, a dog, and even a plane if they are his mother. This might seem silly, since we know that birds only give birth to baby birds. But why doesn't a bird give birth to a crocodile, a cat, or a boat?

The answer lies in a tiny, fascinating bundle of molecules (the smallest particles of a substance) located inside each one of your body's cells! The genetic code that decides the unique features of each species is called deoxyribonucleic acid, or more simply, DNA. So your DNA specifies that, as a human, you will have ten fingers and ten toes, but it gets more specific! DNA is responsible even for your hair color!

Now, DNA carries an incredible amount of information, so how does it all fit inside something as small as a cell?

Structure of DNA

It is DNA's clever structure that allows it to contain millions of instructions in a small space. DNA is built in a double helix. An easy way to picture a double helix is to picture a ladder, now grab either end of the ladder and twist! The spiraled shape you've made is a double helix.

The structure of DNA resembles a twisted ladder, known as a double helix.
DNA double helix

Let's talk about how this twisted ladder is built. First, the rungs (horizontal bars) of the ladder are made of four basic building blocks, or bases: adenine, thymine, cytosine, and guanine. Just like deoxyribonucleic acid is abbreviated DNA, these bases are often referred to by their first letter: A, T, C, and G.

Certain bases fit together perfectly--like two puzzle pieces, they just click! Adenine clicks with thymine, and cytosine clicks with guanine. These matching pairs of bases are called complementary base pairs, and they are what form the rungs of the ladder.

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