wobble hypothesis
The wobble hypothesis is a theory in molecular biology that explains how multiple codons (the set of three nucleotides that encodes for an amino acid) can code for a single amino acid during protein synthesis. This hypothesis explains how the third nucleotide in a codon can vary without affecting the amino acid sequence of a protein. The wobble hypothesis proposes that the third nucleotide can "wobble" or be flexible in its pairing with the corresponding nucleotide in the anticodon of a transfer RNA (tRNA), which brings the amino acid to the ribosome for protein synthesis. This flexibility allows for some degeneracy in the genetic code, where multiple codons can code for the same amino acid, increasing genetic diversity and reducing the likelihood of harmful mutations.
The wobble hypothesis is a concept in molecular biology that explains how certain nucleic acid triplets (codons) can code for more than one amino acid during protein synthesis. In the genetic code, each codon consists of three nucleotides, and each codon typically codes for a specific amino acid. However, there are only 20 common amino acids but 64 possible codons, meaning that there is more than one codon that can code for the same amino acid.
The wobble hypothesis suggests that the specificity of the codon-anticodon interaction is not always strict, particularly at the third nucleotide position of the codon (the wobble position). It states that the base pairing between the third nucleotide of the codon and the corresponding nucleotide in the anticodon of the transfer RNA (tRNA) can be less stringent, allowing for some flexibility in the pairing.
This flexibility arises due to the non-standard hydrogen bonding patterns between the nucleotides at the wobble position. According to the wobble rules proposed by Francis Crick, some non-standard base pairs, such as G-U and I (inosine)-containing base pairs, can form at the wobble position. These non-standard base pairs allow certain tRNAs to recognize more than one codon and still carry the same amino acid.
Overall, the wobble hypothesis explains how the genetic code can be degenerate (having multiple codons for the same amino acid) without compromising the fidelity of protein synthesis. It provides an additional mechanism for the cell to efficiently use its tRNA pool and adapt to variations in codon usage among different organisms.