What is the main function of the Poly (A) tail added to mRNA?

The primary function of the Poly (A) tail added to mRNA is to enhance mRNA stability. The Poly (A) tail, which consists of a long stretch of adenine nucleotides, is added to the 3’ end of the mRNA molecule after transcription. This tail plays a crucial role in protecting the mRNA from degradation by exonucleases in the cytoplasm, thus increasing its overall lifespan and allowing more time for translation into proteins.

Additionally, the Poly (A) tail facilitates the export of the mRNA from the nucleus to the cytoplasm, aids in the initiation of translation, and plays a role in the regulation of protein synthesis. However, its most significant function is arguably in prolonging the stability of the mRNA, which is essential for ensuring that the message can be accurately translated into proteins over a sufficiently long period.

The other options address different aspects of mRNA processing but do not directly relate to the primary role of the Poly (A) tail. For instance, splicing involves the removal of introns from pre-mRNA and is a separate process that occurs prior to the addition of the Poly (A) tail. Identifying exons is also a part of the splicing process rather than being a