Question

You sequence the DNA of the organism, and it was normal at this location, with no mutations. You sequence the mRNA, and it was also normal. Based on your knowledge of protein translation, and any changes in the peptide that you recover, you assume that there has been some of type of change in the translational, not post-translational mechanism due to the radiation. What is/are a plausible guess to the explain the changes in the peptide recovered versus the one predicted and what type of potential change/mutation may have occurred in translation machinery to lead to this effect? Explain your logic and answer.

Answer 1

One mutation which can occur specifically during translation even if the sequence of DNA and mRNA is normal is the incorrect charging of tRNA with amino acid.

We all know that transfer RNA carries anti codon and on the basis of this anticodon, it carries a specific amino acid. The anticodon pairs with codon present all the Messenger RNA and this leads to the addition of amino acid, carried by transfer RNA to the growing polypeptide chain present at tRNA in the P site of ribosome. The addition of amino acid to the transfer RNA according to it anti codon is called as the charging of transfer RNA. Mutation can occur at this step if the transfer RNA picks up a different amino acid which is not encoded by the anti codon it is carrying. So even if there will be correct code on on messenger RNA, there will be correct pairing between codon and anticodon, a wrong amino acid will be added to the growing polypeptide chain.

This is how the defect is during translation and not during replication, transcription and post translational modification.

Please give a high rating.