Which of the following is the amino acid that appears at the n-terminus of all newly translated prokaryotic and eukaryotic polypeptides?
tryptophan
methionine
selenocysteine
glycine

The correct answer is option second - methionine.

Explanation:

During translation, the initiator tRNA binds with a smaller subunit of the ribosome and this assembly bind to the start codon AUG at mRNA molecule in both prokaryotes and eukaryotes and then large subunit bind to this assembly and start polypeptide chain.

So, the first codon is AUG which is start codon and code for methionine in eukaryotes and fMeth in prokaryotes at newly translated prokaryotic and eukaryotic polypeptides at the N- terminus.

Thus, the correct answer is option second - methionine.

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