Final answer:
In prokaryotic cells, ribosomes can begin translating mRNA into proteins before transcription is complete, as there is no nucleus to separate these processes.
Step-by-step explanation:
Ribosomes can attach to prokaryotic messenger RNA before transcription is complete.
This is because in prokaryotic cells, there is no membranous compartmentalization such as a nucleus separating the processes of transcription and translation.
Therefore, a prokaryotic mRNA can start to be translated into protein by ribosomes while the mRNA strand is still being synthesized by RNA polymerase.
This efficient process allows a prokaryotic cell to respond quickly to environmental signals requiring new proteins.
In contrast, eukaryotes have a nucleus that separates transcription and translation processes.
Eukaryotic mRNA must undergo post-transcriptional modifications, including 5' capping, 3' polyadenylation, and intron splicing, before it can be exported from the nucleus and translated by ribosomes in the cytoplasm.