Question

A key modification in the 3′ end of eukaryotic mRNA is the addition of 50 to 250 adenine nucleotides at the 3′ end, forming a poly(A) tail. Which of the following statements is not a salient feature of this polyadenylation reaction?

1) The stability of mRNA transcripts in the cytoplasm is affected by poly(A) tail.
2) Poly(A) tail facilitates the attachment of the ribosomes to the mRNA.
3) Proper poly(A) tail is important for proper nuclear export of mRNA.
4) Poly(A) tail at the 3′ end translates to a long stretch of repeated amino acids.
5) Multiple proteins will recognize and bind to poly(A) tail in the cytoplasm.

Answer 1

Statement 4 is incorrect as the poly(A) tail at the 3' end of mRNA is not translated into protein; instead, it plays roles in mRNA stability, initiation of translation, export from the nucleus, and binding of cytoplasmic proteins.

Step-by-step explanation:

The modification referred to in the question is the addition of a poly(A) tail to the 3' end of eukaryotic mRNA during the process of polyadenylation. Among the given statements, the one that is not a salient feature of this reaction is statement 4: "Poly(A) tail at the 3′ end translates to a long stretch of repeated amino acids." In fact, the poly(A) tail is not translated into a protein sequence; rather, it has several other important roles. Firstly, it affects the stability of mRNA transcripts in the cytoplasm. Secondly, it helps with the attachment of ribosomes to the mRNA, facilitating translation initiation. Thirdly, a proper poly(A) tail is critical for the efficient nuclear export of mRNA. Lastly, multiple proteins in the cytoplasm recognize and bind to the poly(A) tail, serving various functions related to mRNA stability and translation.