Free Custom «RNA Translation and Protein Synthesis» Essay Paper

Translation refers to the process through which messenger RNA is translated into protein(Nair 2004). This does take place through the following steps; Initiation, Elongation and termination. This paper will discuss the process of elongation of poly peptides.Elongation of polypeptidesIt is important to highlight the process of initiation in order to make a clear and smooth transition to the elongation process. The initiation step involves the collection and assembly of the necessary components for the translation process (Nair 2004). These are; the initiation factors (IF1, IF2 &IF3), aminoacyl tRNA, GTP and messenger RNA. The ribosome has three regions i.e. the A, P and E site. These have different purposes (Meisenberg& Simmons, 2006). The A site acts as the site for the entry of the aminoacyl tRNA (Nair 2004). Formation of the peptidyl tRNA occurs at the P site of the ribosome. The E site acts as the site of exit of for the tRNA which has already given amino acid to the growing polypeptide chain(Meisenberg& Simmons, 2006).The process of elongation requires specific non-ribosomal proteins eg in E-coli these are EFs. This step begins with the binding of the appropriate aminoacyl-tRNA to the condon to the Ribosomes A site. The Aminoacyl-tRNA is a tRNA with the capacity to bind to an amino acid. This Aminoacyl-tRNA is able to base pair with the condon on the mRNA (Nair 2004). This requires the use of an elongation factor and a source of energy which in this case is GTP. The elongation factor-Tu (EF-Tu) and GTPase are necessary for this process to occur (Meisenberg& Simmons, 2006). Elongation starts after the arrival of the initiator tRNA at the P site resulting to opening of the A -site through a conformational change (Nair 2004). A new aminoacyl-tRNA is able to bind at the opened A site..The incoming amino-acyl is brought to the A site by an eEF-1a-GTP complex which is hydrolyzed to GDP soon after the t RNA is deposited (Meisenberg& Simmons, 2006). EF-tu and the bound GDP vacate the ribosome this is the proof reading mechanism that discourage misincorporation of near -cognate aa-tRNA (Meisenberg& Simmons, 2006). Now the Aminoacyl tRNA remains at the A site for peptide bond formation (Nair 2004). The peptide attached to the tRNA at the P site is then transferred to the amino group at the aminoacyl tRNA at the A site. This reaction is referred to as transpeptidation and is catalysed by Peptidyltranferase(Nair 2004). The A site now contains peptidyl-tRNA while the P site has a free tRNA (Meisenberg& Simmons, 2006). The free tRNA vacates the P site and the peptydyl-tRNA moves from the A site to the P site.

 

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Translocation is the final elongation stage and is catalyzed by the GTP binding EF-G. Three nucleotides are moved by the ribosome towards the 3 end of the messenger RNA.. The ribosome then continues to translate the remaining condons on the mRNA as more aminoacyl-tRNA bind to the A site until the ribosome reaches a stop condon on mRNA.the ribosome is moved along the mRNA such that the next condon of the mRNA resides under the A site. The e EF-tu is released from the ribosome. The rate of ribosomal protein synthesis is about 20 amino acids per second and the error rate is about 1 for every 10000 amino acids. This process is then followed by termination where the synthesized protein is released from the ribosome.