What is meant by the term 'wobble' in codon-anticodon pairing?

• A. The third position of the codon allows non-Watson-Crick pairing, enabling a single tRNA to recognize multiple codons.
• B. The first position of the codon pairs with the anticodon in a nonstandard way.
• C. Wobble refers to instability of tRNA during charging.
• D. Wobble is the ability of rRNA to catalyze peptide bond formation.

Answer: (A)

Wobble refers to flexible base pairing at the third position of the codon, which allows a single tRNA anticodon to recognize multiple codons. The genetic code is degenerate, meaning many amino acids are encoded by more than one codon that differs in the last base. At this third base, nonstandard or non-Watson-Crick pairings are tolerated, so a tRNA can read several codons for the same amino acid. For example, an anticodon containing inosine can pair with codons ending in U, C, or A, and other noncanonical pairings like G–U can occur. This flexibility reduces the number of different tRNA molecules needed.

The other statements describe processes or aspects not related to wobble: wobble does not concern the first codon position, tRNA charging stability, or rRNA-catalyzed peptide bond formation.