The instructions for who you are come hidden in the cells of your body. They are there from the very beginning. They decide what color eyes or hair you will have and how tall you will be. These instructions also determine whether you are right or left handed, or even how athletic you are. The name for the instructions is DNA, or deoxyribonucleic acid. That’s quite a mouthful so we will just go with DNA. DNA is stored in your cells in a chromosome. Everyone starts out with two sets of chromosomes, one from your mom and one from your dad.

When you look at DNA with a very powerful microscope it looks like a circular staircase. The outside edges of DNA look like two very long strands. The strands are made of sugars and phosphates.  These strands are held together by adenine (A), thymine (T), guanine (G), and cytosine (C). These bases make the steps on the staircase and together the four ingredients and the long strands form a chain that is called a double helix. Remember that I said these strands are in the cells of our bodies? That means if you took all your DNA and flattened it out to look like railroad tracks you could travel all the way around the universe, not once, but twice. That is a lot of information in the tiny space of one cell.

The four bases, or nucleotides, that hold the strands of DNA together are the computer code or recipe for all life. They are mixed together over and over again in pairs. In fact a human has more than 3 billion pairs in their bodies. These pairs of bases tell each cell in your body what their job is. Three nucleotides strung together is a codon, and when you string codons together you create a gene. That gene creates a protein that tells the cell what its job is. Just like when you are building something with legos, nucleotides will only line up in a certain way.

150 years ago there was a monk named Gregor Johan Mendel. He loved everything science, especially the outdoors and plants. He studied botany. Botany is the study of plants. Mendel noticed that you can have two plants that are the same but look different. He grew pea plants that had two different traits next to each other. After a time he observed that the plants began to take characteristics from the parent plant. During his research he realized that some characteristics were stronger than others. He called these the dominant genes. Other characteristics that did not happen often were called recessive genes. Basically this means you may get chromosomes from each parent but some of those genes are stronger than others.  His experiments showed how it is decided what color hair or eyes you might have.