DNA Structure. ­DNA is o­ne of the nucleic acids, information-containing molecules in the cell (ribonucleic acid, or RNA, is the other nucleic acid). DNA is found in the nucleus of every human cell. (See the sidebar at the bottom of the page for more about RNA and different types of cells).he base pairs in DNA are adenine with thymine and cytosine with guanine. DNA has a spiral staircase-like structure. The steps are formed by the nitrogen bases of the nucleotides where adenine pairs with thymine and cytosine with guanine. Photo courtesy U.S. National Library of Medicine.