Deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) are both polynucleotides, polymers of molecules called nucleotides. Nucleotides are composed of three components:

• nitrogen-containing bases
  • the purines: adenine and guanine
  • the pyrimidines: cytosine, thymine (only in DNA), and uracil (only in RNA)
• ribose (in RNA) or deoxyribose (in DNA) sugars
• phosphate (linked to the sugars to form diesters)

In this tutorial we will consider each of the above building blocks and how they are linked together to form both DNA and RNA.