Question

It has been suggested that the poly-A tail on mRNA in eukaryotes functions as a sort of “punchcard”, where each time the mRNA is used for translation, some of the A bases are removed until too few remain and the mRNA is degraded. Describe how we could test this hypothesis and why might such a function exist?

Answer 1

The poly A tail consists of more number of adenosine monophosphate .Poly A tail is added to the mRNA in order to produce mature mRNA for translation. Poly A tail is added to the end of the RNA, and it protects mRNA from enzymatic digestion in cytoplasm and export the mRNA from the nucleus. Over the period of time the tail will be shortend , and when it becomes too short the mRNA will be degraded enzymatically .In some cells the mRNA with such short tails are stored in the cytosol for later activation. i.e., In immature egg cells these short length poly A tail will not be degraded but stored in translationally inactive state, and these are activated during   fertilization by cytoplasmic polyadenylation and this lengthens the shortened tail in order to translate the mRNA.

This hypothesis can be tested in bacteria ,RNA viruses like Influenza A, Corona virus etc….

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