Unfortunately it makes the unambiguous determination of triplets by these methods much more difficult than would be the case if there were only one triplet for each amino acid.
Francis CrickFor simplicity one can think of the + class as having one extra base at some point or other in the genetic message and the - class as having one too few.
Francis CrickThe major credit I think Jim and I deserve is for selecting the right problem and sticking to it. It's true that by blundering about we stumbled on gold, but the fact remains that we were looking for gold.
Francis Crick