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
