The smallest 30S subunit of prokaryotes contains 16S rRNA (ribosomal ribonucleic acid) and 50S subunit contains 5S and 23S rRNA. The small ribosomal subunit 16S rRNA contains Shine-Dalgarno sequence, which forms an attaching by interacting with the sequence on the 5' end of mRNA (messenger ribonucleic acid). The pairing poses the ribosome, to correctly initiate translation at AUG, which is the start codon for protein synthesis. The translation process continues until the ribosomes are signalled by one of the three stop codons: UAA, UAG and UGA.
Whereas, if eukaryotic mRNA is added to the test tube containing a bacterial cell extract with all the components need for translation cannot produce a radioactive protein because the eukaryotic mRNA does not contain the Shine-Dalgarno sequence that positions the ribosome to correctly initiate the translation process.