Final answer:
RNA is processed in the eukaryotic nucleus where it undergoes post-transcriptional modifications including splicing, 5' capping, and 3' polyadenylation to become mature mRNA ready for translation in the cytoplasm.
Step-by-step explanation:
RNA is processed in the nucleus of eukaryotic cells. During this post-transcriptional modification, several key changes occur to the primary transcript (pre-mRNA) to transform it into mature mRNA. Initially, the pre-mRNA receives a 5' cap, which is a modified guanine nucleotide that aids in stability and facilitates the future translation process. Splicing is the next crucial step where introns (non-coding regions) are removed and exons (coding regions) are joined together. Finally, a polyadenylation signal prompts the addition of a poly-A tail consisting of adenine nucleotides at the 3' end. This sequence of RNA splicing, 5' capping, and 3' polyadenylation are critical for mRNA stability and export from the nucleus to the cytoplasm where protein synthesis occurs.