Final answer:
Pre-mRNA processing involves the addition of a 5' cap and a poly-A tail, and the splicing out of introns to produce a mature mRNA ready for translation. These steps are critical for the mRNA's stability, nuclear export, and translational efficiency.
Step-by-step explanation:
Before pre-mRNA is sent out to the cytoplasm, it undergoes several critical processing steps which are essential for creating a mature mRNA molecule that can be translated into a protein. The three main steps in pre-mRNA processing are:
5' capping: The addition of a 7-methylguanosine cap at the 5' end of the pre-mRNA, which is crucial for the protection of the RNA from enzymatic degradation, as well as being recognized by factors necessary for protein synthesis initiation.
Splicing: The removal of introns (non-coding regions) from the pre-mRNA and the ligation of exons (coding regions), creating a continuous coding sequence. This process is critical for the accuracy of the amino acid sequence that will be translated from the mRNA.
These modifications ensure the stability and functionality of the mature mRNA, preparing it for transport through the nuclear pore to the cytoplasm where translation occurs