WOBBLE HYPOTHESIS AND ITS CONTRIBUTION TO THE DEGENERACY OF GENETIC CODE

The wobble hypothesis, proposed by Francis Crick in 1966, explains the degeneracy of the genetic code. The genetic code is degenerate, meaning that most amino acids are encoded by more than one codon. The wobble hypothesis provides an explanation for this phenomenon by focusing on the third base of the codon and the first base of the anticodon in tRNA.

Wobble Hypothesis Explanation

According to the wobble hypothesis, the 5’ end of the anticodon in tRNA can form non-standard base pairing with more than one kind of base at the 3’ end of the codon in mRNA. This flexibility in base pairing is due to a phenomenon known as “wobble” or “codon-anticodon wobble.” The wobble rules allow for some relaxation of base-pairing specificity at the third position of the codon, which means that a single tRNA molecule can recognize more than one codon.

Contribution to Degeneracy of Genetic Code

The wobble hypothesis contributes significantly to the degeneracy of the genetic code. By allowing some flexibility in base pairing between the codon and anticodon, it enables a single tRNA species to recognize multiple synonymous codons. This means that even though there are 64 possible codons (4 nucleotides at each of the three positions), there are only 20 standard amino acids and a few additional codons for start and stop signals. The wobble hypothesis helps explain how this limited number of tRNA molecules can effectively decode all 64 possible codons.

Implications for Protein Synthesis

The wobble hypothesis has important implications for protein synthesis. It allows cells to produce proteins efficiently without requiring a separate tRNA molecule for each synonymous codon. This economizes on the number of tRNA genes that need to be present in the genome and simplifies the process of translation.

In summary, the wobble hypothesis provides a molecular explanation for the degeneracy of the genetic code by allowing for flexibility in base pairing between certain codons and anticodons. This flexibility enables a limited set of tRNA molecules to recognize multiple synonymous codons, contributing to the efficiency and economy of protein synthesis.