nucleotides

• Nucleotides are the chemical building blocks of DNA and RNA.
• Each nucleotide consists of:

  • a phosphate group
  • a five-carbon sugar
  • deoxyribose sugar in DNA
  • ribose sugar in RNA
  • a nitrogenous base
• Purines = double ring molecular structure A = adenine G = guanine
• Pyrimidines = one ring molecular structure T = thymine (only in DNA) C = cytosine U = uracil (only in RNA)