Nucleotides and phosphodiester bonds

• Nucleotides


  Monomers that make up DNA and RNA, which are nucleic acids
• DNA and RNA


  • Polymers made up of many repeating nucleotide units
• Nucleotide


  • Consists of a pentose sugar, a nitrogen-containing organic base, and a phosphate group
• Components of a DNA nucleotide

  • Deoxyribose sugar with hydrogen at the 2' position
  • Phosphate group
  • One of four nitrogenous bases - adenine (A), cytosine(C), guanine(G) or thymine(T)
• Components of an RNA nucleotide


  • Ribose sugar with a hydroxyl (OH) group at the 2' position
  • Phosphate group
  • One of four nitrogenous bases - adenine (A), cytosine(C), guanine(G) or uracil (U)
• Purines


  Nitrogenous base molecules with a double ring structure (adenine and guanine)
• Pyrimidines


  Nitrogenous base molecules with a single ring structure (cytosine, thymine and uracil)
• Phosphodiester bond formation


  1. Condensation reaction between the phosphate group of one nucleotide and the pentose sugar of the next nucleotide

  2. Produces a chain of alternating phosphate groups and pentose sugars known as the sugar-phosphate backbone
• Polynucleotide breakdown


  Requires the breakage of phosphodiester bonds
• The presence of the 2' hydroxyl group makes RNA more susceptible to hydrolysis
• DNA is the storage molecule and RNA is the transport molecule with a shorter molecular lifespan