Medicine & USMLE


Amino Acids
  1. Serine
  2. Asparagine
  3. Alanine
  4. Valine
  5. Leucine
  6. Isoleucine
  7. Phenylalanine
  8. Tryptophan
  9. Methionine
  10. Proline
  11. Glycine
  12. Threonine
  13. Cysteine
  14. Tyrosine
  15. Glutamine
  16. Aspartate
  17. Glutamate
  18. Histidine
  19. Lysine
  20. Arginine


Glycine, which is abbreviated as the 3 letters Gly as well as the single letter G, is one of the 20 amino acids that make up proteins in our body. Glycine’s R-group is a single hydrogen atom, which makes it a non-polar, hydrophobic amino acid. Further, glycine is the only non-chiral amino acid because its alpha carbon is bonded to two identical hydrogens, creating an internal plane of symmetry. Glycine’s small R-group being just a hydrogen allows proteins incorporating it to make very tight turns, giving the polypeptide chain a lot of flexibility to twist and turn.

Key Points

  • Glycine
    • Abbreviations
      • Gly, G
    • Chemical Structure
    • R-group: -H
      • Symmetrical plane around the alpha carbon leads to achirality
      • Small R group also allows for conformational and steric flexibility
    • Polarity
      • Non-polar (lipid soluble/hydrophobic)
    • Charge at pH 7
      • Neutral (0)
    • Other Information 
      • Only non-chiral amino acid
      • Structure can allow for tighter turns in protein structure than other AAs
        • Allows for conformational flexibility