Eukaryotes show more modifications to their RNA molecules compared to prokaryotes because eukaryotic mRNA molecules have to undergo several processing steps before they can be translated into proteins. These processing steps include capping, splicing, and polyadenylation, which result in the addition of a 5' cap and a 3' poly(A) tail and the removal of introns from the RNA molecule.
These modifications are important for several reasons. Firstly, the 5' cap and the poly(A) tail help to stabilize the mRNA molecule by protecting it from degradation by nucleases. Secondly, splicing allows for the production of multiple protein isoforms from a single gene by removing non-coding introns and recombining exons in different ways. Thirdly, the modifications facilitate the export of mRNA from the nucleus to the cytoplasm, where translation occurs.
Additionally, eukaryotes have more complex regulatory mechanisms that require more diverse and complex RNA molecules. For example, microRNAs, small non-coding RNA molecules that regulate gene expression, are unique to eukaryotes and require extensive RNA processing and modifications.