What is a primary consequence of wobble base pairing for tRNA usage in the cell?

• A. It reduces the number of tRNA species needed to cover all codons for amino acids.
• B. It eliminates codon degeneracy entirely.
• C. It causes amino acid misincorporation frequently.
• D. It invalidates the genetic code.

Answer: (A)

Wobble base pairing at the third position of the codon lets a single tRNA anticodon recognize multiple codons that specify the same amino acid. The first two bases pair strongly and specifically, while the third position can pair in a less strict way, so one tRNA can read several codons that differ at that spot. This reduces the number of distinct tRNA species the cell must maintain to cover all codons for amino acids, making translation more efficient without sacrificing accuracy. The genetic code remains functional and degenerate—there are still multiple codons for some amino acids, but wobble lets those codons be matched by fewer tRNA types. Wobble does not cause widespread misincorporation, since the ribosome and the charging enzymes preserve fidelity within these permissive pairings. It also doesn’t invalidate the genetic code.