Why is it that the primary transcript in prokaryotes can immediately serve as mrna while in eukaryotes it undergoes elaborate multistep processing? (select all that apply.) primary transcripts in eukaryotes contain introns that have to be removed. general transcription factors in eukaryotes are unable to enter the nucleus. prokaryotes do not have a nuclear envelope and the ribosome can start translation even before transcription ends. all of these choices are correct. a 5′ cap is added to the prokaryotic primary transcript allowing the ribosome to start translation immediately?