DNA stands for Deoxyribonucleic Acid. It is the molecule that holds all the genetic information that makes you, you!

Its structure is sort of like a twisted ladder. It has a backbone, and thousands to millions of rungs. The radius of one strand of DNA is about one nanometer. By the time I just read this, your fingernails would have grown about a nanometer. In other words, a strand of hair is about 75,000 nanometers wide. So just imagine how tiny these are!!

The chemical building blocks that make up DNA are called nucleotides. The backbone of DNA is made up of alternating phosphate and sugar combinations. The nucleotides link into chains to form a strand of DNA.  

In organisms called eukaryotes, like humans, DNA is found inside a part of a cell called the nucleus. Because the cell is very small, and because organisms have many DNA molecules per cell, each DNA molecule must be tightly packaged. This packaged form of the DNA is called a chromosome.

The rungs of the ladder are made up for combinations of four nitrogen bases. These chemical bonds include, adenine, thymine, guanine, and cytosine. There are only specific combinations that these four nitrogen bases can go together with.