Protein Synthesis in Prokaryotic vs Eukaryotic
Protein synthesis has its steps in order in a very highly sequenced manner inside each cell of the entire biological word, but there are small identities in each. However, there are seriously considerable differences between prokaryotic and eukaryotic protein synthesizing pathways, despite the end result is always a protein in both cases. The components of the two types of cells could be the main reason for those to be different from each other. However, the main steps of transcription, RNA processing, and Translation are the same in both prokaryotes and eukaryotes. A general account on protein synthesis is presented in this article followed by easy to digest discussions of main considerable differences between each other.
Protein Synthesis
Protein synthesis is a biological process that takes place inside the cells of organisms in three main steps known as Transcription, RNA processing, and Translation. In the transcription step, nucleotide sequence of the gene in the DNA strand is transcribed into RNA. This first step is highly similar to the DNA replication except the result is a strand on RNA in protein synthesis. The DNA strand being dismantled with DNA helicase enzyme, RNA polymerase is attached at the specific place of the start of the gene known as promoter, and RNA strand is synthesized along the gene. This newly formed RNA strand is known as the messenger RNA (mRNA).
The mRNA strand takes the nucleotide sequence to the ribosomes for the RNA processing. Specific tRNA (transfer RNA) molecules will recognize the relevant amino acids in the cytoplasm. After that, tRNA molecules are attached to the specific amino acids. In each tRNA molecule, there is a sequence of three nucleotides. A ribosome in the cytoplasm is attached to the mRNA strand, and the starting codon (the promoter) is identified. The tRNA molecules with the corresponding nucleotides for the mRNA sequence are moved into the large subunit of the ribosome. As the tRNA molecules come to the ribosome, the corresponding amino acid is bonded with the next amino acid in the sequence through a peptide bond. This last step is known as translation; indeed, this is where the actual protein synthesis takes place.
The shape of the protein is determined through the different types of amino acids in the chain, which were attached to tRNA molecules, but tRNA are specific to the mRNA sequence. Hence, it is clear that the protein molecules depict the information stored in the DNA molecule. However, protein synthesis could be initiated from an RNA strand, as well.
What is the difference between Protein Synthesis in Prokaryotic and Eukaryotic?
• As the transcription step takes place, the ribosomes are capable of associating with the forming mRNA strand in prokaryotes as they do not have a nuclear envelope to enclose the nucleic acids. However, mRNA can associate with the ribosomes after the strand is moved out of the nucleus in eukaryotes.
• Therefore, it becomes clear that the translation step of the process has already been started before the transcription is complete in prokaryotes, whereas the two steps take place far apart in eukaryotes. In other words, RNA processing does not take place in prokaryotic synthesis, but it does in the eukaryotic process.
• Only one gene is expressed in one full process of protein synthesis in eukaryotes while there are often several genes expressed in bacterial (prokaryotic) protein synthesis from one mRNA strand. In other words, clustered genes (known as Operons) can be expressed by prokaryotes but not the eukaryotes could.
• There are non-coding DNA sequences in eukaryotic nucleic acids known as Introns but not in prokaryotes. The mRNA in eukaryotes removes the introns from its strand before leaving the nucleus, which is in contrast with the simple formation of mRNA strand in prokaryotes.