USMLE

Nucleotides vs Nucleosides

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Nucleic Acids
  1. Adenine
  2. Guanine
  3. Cytosine
  4. Thymine
  5. Uracil
  6. Nucleotides vs Nucleosides

Summary

Nucleotides and nucleosides are related compounds that serve as the building blocks of nucleic acids, like DNA and RNA. Nucleotides are composed of 3-parts: a sugar, a nitrogenous base, and one or more phosphate groups. Nucleosides are composed of 2-parts: a nitrogenous base and a sugar. Nucleosides do not contain any phosphates. The sugar in nucleotides and nucleosides can be either ribose or its deoxygenated form, deoxyribose. Ribose is the central sugar in RNA, while deoxyribose is the central sugar in DNA.

Key Points

  • Nucleoside
    • Components
      • Nitrogenous Base
      • Sugar
    • Structure
      • The nitrogenous base attaches to C-1’ of the sugar

    • Nucleotide 
      • Function
        • The building blocks that form chains to create the nucleic acids, DNA and RNA
      • Components
        • Nitrogenous Base
        • Sugar
          • Ribose in RNA and Deoxyribose in DNA
        • Phosphate Group 
          • Adding one or more phosphates to a nucleoside makes a nucleotide
      • Structure
        • The sugar molecule has a central position in the nucleotide
          • The nitrogenous base attaches to C-1’ of the sugar
          • The phosphate group attaches to C-5’ of the sugar