When isolated from a cell and stretched out, DNA looks like a twisted ladder. This shape is called a double helix. The sides of the DNA ladder are called the backbone and the steps (also called rungs) of the ladder are pairs of small chemicals called bases. There are four types of chemical bases in DNA: Adenine (A), Cytosine (C), Guanine (G), and Thymine (T). They form pairs in very speciﬁc ways: Adenine (A) always pairs with Thymine (T) and Cytosine (C) always pairs with Guanine (G). Can you construct a DNA model and then eat it too?