Question Video: Explaining the Significance of the UTR in Messenger RNA Biology

Consider the messenger RNA. The blue sequence is commonly called the untranslated region (UTR) and finishes right before the start codon, shown in red. What does this UTR sequence contain?

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Video Transcript

Consider this messenger RNA. The blue sequence is commonly called the untranslated region, UTR, and finishes right before the start codon, shown in red. What does this UTR sequence contain? (A) The UTR sequence contains the DNA polymerase binding site. (B) The UTR sequence contains the mitochondrial binding site. (C) The UTR sequence contains the ribosome binding site. (D) The UTR sequence contains the DNA binding site.

You may recall that a gene in DNA can be converted into a protein in a couple of steps. The first step is transcription, where the gene is copied to make an mRNA transcript. Then, the sequence of nucleotides in mRNA is translated into a sequence of amino acids to form a polypeptide, which can then fold to form a protein. During translation, the mRNA binds to the ribosome. The ribosome matches three nucleotide segments of the mRNA, called codons, with specific amino acids.

In the mRNA sequence in this question, we can see one of these codons here in red. This is called a start codon because this is where translation begins. The start codon actually codes for the amino acid methionine. After the start codon, each codon is matched to its specific amino acid until translation is complete and the polypeptide is released.

The five prime end of the mRNA that precedes the start codon is the untranslated region, or the UTR. This site contains the ribosome binding site that allows the mRNA to bind to the ribosome. Therefore, the option that best describes what the UTR sequence contains is given by answer choice (C). The UTR sequence contains the ribosome binding site.

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