The structure of DNA (Deoxyribonucleic acid) is made up of a long sequence of molecular components that makes a chain that resembles a twisted ladder. This chain has 4 different bases, (T) Thymine,(A) Adenine, (C) Cytosine and (G) Guanine and put together makes instructions for making a living organism. The bases T & A always go together and C & G go together. All living things have DNA molecules inside. These sequences decide what typer of physical characteristics you develop and DNA is passed down from you parents and grandparents.