A ribonucleotide tri-phosphate (rNTP) is composed of a ribose sugar, 3 phosphate groups attached via diester bonds to the 5 oxygen on the ribose and a nitrogenous base attached to the 1 carbon on the ribose. rNTP's are also referred to as NTPs while the deoxyribose version is referred to as dNTPs. The nitrogenous base can either be a purine such as a Adenine or Guanine or a pyrimidine such as a Uracil or Cytosine. rNTPs have significant biological uses, they can serve as building blocks of RNA synthesis, primers in DNA replication, stores of chemical energy, chiefly Adenosine triphosphate (ATP) and more.