Translation is the term used to describe the polymerization of amino acids into a polypeptide, constituting the biological process by which proteins are synthesized is called translation.
Translation happens in following main steps:
Initiation, Elongation, Translocation, Termination
Initiation:
1. The initiation phase involves the assembly of ribosomes around the target mRNA.
2. Ribosomes, known as the sites of protein synthesis, play a crucial role in this process.
3. The first tRNA becomes attached specifically at the start codon on the mRNA.
4. It’s important to note that a codon is a triplet of nucleotides that codes for a specific amino acid in the context of protein synthesis.
Elongation:
1. During the elongation phase of protein synthesis, the transfer RNA (tRNA) plays a crucial role.
2. The tRNA acts by transferring an amino acid to the tRNA molecule that corresponds to the next codon in the mRNA sequence.
3. This phase is characterized by the sequential addition of amino acids, forming an ever-lengthening polypeptide chain.
4. The step of elongation is central to the overall process of protein synthesis, constituting the majority of the molecular events involved in building the protein.
Translocation:
During the process of translocation in protein synthesis, the ribosome shifts along the mRNA strand to the subsequent codon, thereby perpetuating the sequential progression. This iterative movement facilitates the ongoing synthesis of an amino acid chain as each codon is read and the corresponding amino acid is added to the growing polypeptide.
Termination:
1. The termination or stop codon serves as a signal for the ribosome to halt the process of translation.
2. When the ribosome encounters a stop codon (such as UAA, UAG, or UGA) in the mRNA sequence, it recognizes it as the termination point for protein synthesis.
3. The release factor, a protein that is not an aminoacyl-tRNA but rather facilitates the termination process, binds to the stop codon.
4. This binding triggers the hydrolysis of the bond between the final tRNA molecule and the completed polypeptide chain.
5. As a result of this hydrolysis, the ribosome releases the newly synthesized polypeptide chain.
6. The released polypeptide then undergoes further folding and post-translational modifications to attain its functional three-dimensional structure.
7. Meanwhile, the ribosome, now free from the mRNA template, can be recycled for subsequent rounds of protein synthesis.