Explanation
All non-sense codons have the nucleotide base Uracil (U) as their first base. Therefore, the answer is C) Uracil.
A codon is a three-nucleotide sequence that codes for a specific amino acid or serves as a stop signal in the genetic code. There are three non-sense codons, also known as stop codons, that signal the end of protein synthesis: UAA, UAG, and UGA. These codons do not code for any amino acid, but instead signal for the release factor to stop translation and release the completed polypeptide chain.
In RNA, uracil takes the place of thymine (T) found in DNA, and it only pairs with adenine (A) through hydrogen bonds. Therefore, all stop codons in mRNA have the first base as U, which pairs with A in the anticodon of the tRNA.
