Practice question

Attenuation requires physical and temporal coupling between transcription and translation characteristic of prokaryotes lacking nuclear membrane barrier. As RNA polymerase synthesizes leader messenger RNA, ribosome loads onto five prime end and follows closely behind, translating leader peptide in lockstep. Dynamic distance between macromolecular machineries determines which RNA hairpins can form among complementary regions. When ribosome stalls due to scarcity of charged Trp-tRNA, alternative secondary structures emerge dictating termination decision. Eukaryotic nucleus separates transcription and translation in space and time, precluding such coupling. Requirement explains why attenuation absent where processes spatially segregated and temporally unlinked in eukaryotes.