wobble hypothesis

There are fewer tRNAs in most organisms than there are codons, so Crick proposed that the interaction between bases at the third (3′) position of the codon and the first (5′) position of the anticodon on the tRNA followed different rules than the A-T and G-C base pairing in DNA. The suggestion was that a C in that position in the anticodon could "wobble" and pair with either a G or A in the third position of the codon, while a U in the same position could pair with either