Messenger RNAs undergo 5' capping, splicing, 3'-end processing, and export before translation in the cytoplasm. It has become clear that these mRNA processing events are tightly coupled and have a profound effect on the fate of the resulting transcript. This processing is represented by modifications of the pre-mRNA and loading of various protein factors. The sum of protein factors that stay with the mRNA as a result of processing is modified over the life of the transcript, conferring significant regulation to its expression. As mRNA processing events involve different cellular machinery Fig.
NCBI Bookshelf. Cooper GM. The Cell: A Molecular Approach. Sunderland MA : Sinauer Associates; Proteins are synthesized from mRNA templates by a process that has been highly conserved throughout evolution reviewed in Chapter 3. Each amino acid is specified by three bases a codon in the mRNA, according to a nearly universal genetic code.
This page has been archived and is no longer updated. The genes in DNA encode protein molecules, which are the "workhorses" of the cell , carrying out all the functions necessary for life. For example, enzymes, including those that metabolize nutrients and synthesize new cellular constituents, as well as DNA polymerases and other enzymes that make copies of DNA during cell division , are all proteins. In the simplest sense, expressing a gene means manufacturing its corresponding protein, and this multilayered process has two major steps. The resulting mRNA is a single-stranded copy of the gene, which next must be translated into a protein molecule.
The eukaryotic pre-mRNA undergoes extensive processing before it is ready to be translated. The additional steps involved in eukaryotic mRNA maturation create a molecule with a much longer half-life than a prokaryotic mRNA. Eukaryotic mRNAs last for several hours, whereas the typical E.