Nucleic acids are organic compounds that are made up of five elements: carbon, hydrogen, oxygen, nitrogen, and phosphorous/03%3A_Molecular_Level-_Biomolecules_the_Organic_Compounds_Associated_With_Living_Organisms/3.06%3A_Nucleic_Acids). These elements are arranged in a specific way to form nucleotides, which are the building blocks of nucleic acids. Nucleotides consist of three parts: a sugar molecule, a nitrogen-containing base, and a phosphate group/03%3A_Molecular_Level-_Biomolecules_the_Organic_Compounds_Associated_With_Living_Organisms/3.06%3A_Nucleic_Acids). The sugar molecule in DNA is called deoxyribose, while in RNA it is called ribose. The nitrogen-containing bases in DNA are adenine, thymine, guanine, and cytosine, while in RNA, uracil replaces thymine/03%3A_Molecular_Level-_Biomolecules_the_Organic_Compounds_Associated_With_Living_Organisms/3.06%3A_Nucleic_Acids). The phosphate group links the nucleotides together to form the sugar-phosphate backbone of the nucleic acid.