* Added during processing: After transcription (the process of making mRNA from DNA), the mRNA molecule undergoes several modifications before it leaves the nucleus. One of these modifications is the addition of a poly(A) tail to the 3' end of the mRNA. This tail is a string of 100-250 adenine (A) nucleotides.
* Functions of the poly(A) tail: The poly(A) tail plays several important roles in mRNA function:
* Protection: It protects the mRNA molecule from degradation by enzymes in the cytoplasm.
* Export: It helps the mRNA molecule to be exported from the nucleus to the cytoplasm, where protein synthesis takes place.
* Translation initiation: It plays a role in initiating translation, the process of reading the mRNA code to make a protein.
* Stability: The poly(A) tail influences how long the mRNA molecule persists in the cytoplasm, affecting how much protein is produced.
In summary, the term "poly tail" is a shorthand way of referring to the poly(A) tail, which is a crucial feature of processed mRNA molecules.
