The genetic code has only ~20 amino acids but has 64 different codon combinations

  • Consequently, the genetic code is said to show degeneracy – more than one codon may code for a single amino acid

Due to the shape of the tRNA molecule, the third base of an anticodon is not orientated optimally for base pairing

  • Consequently, this third base is less discriminatory towards complementary pairing 
  • This is why degeneracy always occurs in the third base of a codon (this site is known as the wobble position)

Degeneracy of the genetic code allows for the occurrence of silent mutations – whereby a change in the DNA sequence does not alter the polypeptide sequence

The Wobble Hypothesis

wobble hypothesis