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Translation in prokaryotes and eukaryotes differs mainly in terms of location, initiation factors, and the speed of the process.
In prokaryotes, translation occurs in the cytoplasm and can start before transcription is finished, due to the absence of a nuclear membrane. This simultaneous transcription and translation is known as 'coupled transcription-translation'. In contrast, eukaryotes have a nuclear membrane that separates the processes of transcription and translation. Transcription occurs in the nucleus, and the mRNA is then transported to the cytoplasm where translation takes place.
The initiation of translation also differs between prokaryotes and eukaryotes. In prokaryotes, the initiation of translation begins when the small ribosomal subunit binds to a specific sequence on the mRNA known as the Shine-Dalgarno sequence. This sequence is located a few nucleotides upstream of the start codon (AUG). In contrast, eukaryotic translation initiation involves the binding of several initiation factors and the small ribosomal subunit to the 5' cap of the mRNA. The complex then scans along the mRNA until it finds the start codon.
The speed of translation is another key difference. Prokaryotes have a faster rate of translation compared to eukaryotes. This is because prokaryotes have a smaller cell size and simpler cellular structure, which allows for a more rapid response to environmental changes. On the other hand, eukaryotes have a slower rate of translation, which is thought to be due to the complexity of their cellular structure and the need for more stringent control over protein synthesis.
Lastly, the termination of translation in both prokaryotes and eukaryotes is similar, involving a stop codon and release factors. However, in eukaryotes, there is an additional process known as nonsense-mediated mRNA decay, which degrades mRNAs that have premature stop codons to prevent the production of faulty proteins. This process is not present in prokaryotes.
In summary, while the basic process of translation is conserved between prokaryotes and eukaryotes, there are key differences in terms of location, initiation factors, speed, and mRNA surveillance mechanisms. These differences reflect the varying levels of complexity and control in protein synthesis between these two types of organisms.
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