Why are Eukaryotic MRNAs Not Polycistronic, Unlike Some Bacterial Transcripts

Question

Why are eukaryotic mRNAs not polycistronic, unlike some bacterial transcripts?
A) The eukaryotic ribosome must bind to the 5' end of the mRNA and scan, while the bacterial ribosome can bind to a Shine- Delgarno sequence anywhere in the mRNA.
B) Bacteria couple their translation with transcription, while eukaryotes do not.
C) Eukaryote's genetic code is non- overlapping, and so coding sequences cannot overlap on the same mRNA.
D) Eukaryotes have more complex translational machinery than bacteria that is also less efficient in initiating translation.
E) Eukaryotic mRNAs are generally shorter than bacteria mRNAs, and so do not contain sufficient information to encode additional polypeptides.

Accepted Answer

Eukaryotic ribosomes require a 5' cap to initiate translation and scan for the start codon, unlike bacterial ribosomes that can initiate translation at multiple internal sites using Shine-Dalgarno sequences.