Long chains of nucleotides are called nucleic acids. Two types of nucleic acids are found in organisms: deoxyribonucleic acid and ribonucleic acid. DNA consists of two nucleotide chains bonded to and wrapped around one another in a twisted ladder shape called a double helix.
A nucleotide contains three components: a phosphate group, a sugar and a nitrogenous base. The phosphate group and sugar are bonded together to make the backbone portion of a nucleic acid. In DNA, the sugar is deoxyribose; in RNA, the sugar is ribose. The sugar molecule then binds to one of several nitrogenous bases. With DNA, the possible nitrogenous bases are adenine, thymine, guanine and cytosine. For RNA, the nitrogenous bases are the same as with DNA, except that RNA uses uracil in place of thymine. Nucleotides are bound to one another by phosphodiester bonds, which links the phosphate group of one nucleotide to the sugar molecule of another.