What do a person, a daisy, a fish, and a beetle have in common? They're all made of cells! That's right, even YOU are made of trillions of tiny cells. But if all living things are made of cells, what makes each one unique? You're different from a snail, a tree, and even your best friend because of your DNA, the unique genetic code found in every cell in your body. You can't see DNA's structure (even with a powerful microscope), but you'll make a model of it in this activity.