Prokaryotic Protein Synthesis vs. Eukaryotic Protein Synthesis — What's the Difference?

Prokaryotic protein synthesis is characterized by its occurrence solely in the cytoplasm due to the absence of a nucleus, facilitating the coupling of transcription and translation. In contrast, eukaryotic protein synthesis can occur both in the cytoplasm and on the rough endoplasmic reticulum, with transcription and translation processes being spatially and temporally separated due to the presence of a nuclear membrane.

The initiation phase of protein synthesis in prokaryotes requires fewer initiation factors and is generally simpler, reflecting the organisms' overall simpler structure. On the other hand, eukaryotic protein synthesis involves a more complex set of initiation factors and additional processes like capping, splicing, and polyadenylation of mRNA before translation can occur.

In prokaryotes, ribosomes can attach to mRNA and begin translation even before transcription has finished, thanks to the proximity of these processes. Eukaryotes, however, must transport mRNA out of the nucleus and often modify it before translation begins, highlighting a more compartmentalized and regulated approach.

The ribosomes of prokaryotes (70S) are smaller and slightly different in structure and composition than those of eukaryotes (80S), which affects the mechanisms of translation and the sensitivity to certain antibiotics. This difference underlines the distinct evolutionary paths and cellular complexities of these two life forms.

The post-translational modifications in eukaryotic proteins are generally more complex and varied, including folding, cleavage, and addition of various functional groups, reflecting the higher complexity and specificity required by eukaryotic cells. Prokaryotic proteins also undergo post-translational modifications, but these are typically simpler and less diverse.