Once a strand of mRNA is made from the corresponding DNA template it is referred to as a primary transcript. In Eukaryotes, this primary transcript must first be modified before heading out into the harsh environment of the cytoplasm on its way to the ribosome. In the cytoplasm there are numerous digestive enzymes and other molecules that could interact with the mRNA molecule. In no more than three sentences, describe the modifications that must be made to a primary transcript before it can leave the nucleus as a secondary transcript.