Each end of a pre-mRNA molecule is modified in a particular way (Fig. 17.11) ¾The 5′end receives a modified nucleotide 5′cap ¾The 3′end gets a poly-A tail These modifications share several functions ¾They seem to facilitate the export of mRNA to the cytoplasm ¾They protectmRNA from hydrolytic enzymes ¾They help ribosomes attach to the 5′end (translation)