Here's an interesting question that maybe someone here can answer. The question revolves around the fact that codons have associated anti-codons by way of charged tRNA (if my memory serves). I have been wondering about the 3 so-called stop codons, those codons that serve as a 'full stop' as it were. I understand that these 3 'stop codons' have no associated, or complimentary, anticodon/tRNA. Thus, when a ribosome encounters them (via mRNA), there are no more amino acids gathered and the amino acid chain breaks off etc. My question is: How come there is no anti-codon/tRNA complex for a stop codon? Are such potentially befitting tRNA's destroyed somehow, or is there some physiochemical reason why (just) these 3 particular anti-codons cannot form? Seems to me that, for life (as we know it), it is crucial to have a stop codon (like the importance of full stops in text). This means that it is either 'luck' that three codons do not have anti-codons or that there is some cellular mechanism to destroy them. The former might seem most plausible. But then again, why? Why shouldn't all codons have associated tRNA anti-codon complexes?
To further confuse the issue, there are apparently certain organisms in which the three stop-codons DO have anti-codons. Which supports the latter idea that there is a cellular mechanism to destroy any corresponding anti-codons for the stop codons. But then this begs the question as to how such a mechanism got started. Anyhow, I will be much obliged if anyone on this forum can shed light on this mystery. After all, I am assuming that the reason why stop codons do not have complimentary anti-codon tRNAs has been firmly established by geneticists.
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