As we can see on the picture above, translation occurs after transcription of DNA into RNA is done. After that, RNA will further modify into mRNA, rRNA, and tRNA. Then, mRNA will be transported into the cytoplasm. At cytoplasm, mRNA will be translated into amino acid sequences based on the genetic code that was carried by mRNA. Within a gene, information for the amino acid sequence of a protein is encoded in a triplet code or also called as codon. This triplet code must not be overlapping and continuous throughout the strand. The genetic code in form of codon is shown below.
Based on the codon shown above, each of them will be translated into amino acid before bonded to form protein. Before that, we need to know the requirement and the steps needed in order for mRNA to be translated into protein. The requirements are mRNA as codons, tRNA as anti-codons, ribosomes and various protein factors. There were several steps that must be followed such as amino acid activation, chain initiation, chain elongation and chain termination.
The first step is amino acid activation. In this step, amino acid must be activated by tRNA and aminoacyl-tRNA synthetases to form aminoacyl-tRNA before being incorporated into growing protein chain.
Then, chain initiation will take place. It requires tRNA, initiation codon, 30S and 50S ribosomal units, initiation factors, GTP and Mg2+. In initiation steps, all ribosomes, tRNA and the first amino acid will assemble at mRNA specifically at the start codon which is AUG. tRNA will carry the anticodon which is AUC which complements to its codon. Before tRNA attach to mRNA, first amino acid, methionine will bind with tRNA and move with tRNA toward the ribosomes. After that, chain elongation takes place. In this stage, the chain of amino acids will be elongated via formation of peptide bonds. After the first aminoacyl- tRNA is attached to P site, the second aminoacyl-tRNA will bound at A site of the ribosome. Then, peptide bond will be formed between these two amino acids on the both side. The old aminoacyl-tRNA will exit from the ribosome through E site and the new one will shift into the P site allowing another aminoacyl-tRNA to bound on A site. The formation of peptide bond is a continuous process thus it will be forming a chain of amino acids or known as polypeptide.
Lastly, chain termination will take place. After a long continuous process of formation of peptide bonds, eventually, the ribosomes reaching a point called as a stop codon. Stop codons does not have any tRNA thus there will be no aminoacyl-tRNA will be attached to its codon causing a disruption in the process. Formation of peptide bonds will stop and the old aminoacyl-tRNA will exit from the ribosome through E site. After that, all the ribosomal units will dissociate with the aid of release factors thus setting the polypeptide free to go. The newly synthesized polypeptide undergo posttranslational modification thus they will be modified before they reach their final form. The video below shows the whole process of translation.
The first step is amino acid activation. In this step, amino acid must be activated by tRNA and aminoacyl-tRNA synthetases to form aminoacyl-tRNA before being incorporated into growing protein chain.
Then, chain initiation will take place. It requires tRNA, initiation codon, 30S and 50S ribosomal units, initiation factors, GTP and Mg2+. In initiation steps, all ribosomes, tRNA and the first amino acid will assemble at mRNA specifically at the start codon which is AUG. tRNA will carry the anticodon which is AUC which complements to its codon. Before tRNA attach to mRNA, first amino acid, methionine will bind with tRNA and move with tRNA toward the ribosomes. After that, chain elongation takes place. In this stage, the chain of amino acids will be elongated via formation of peptide bonds. After the first aminoacyl- tRNA is attached to P site, the second aminoacyl-tRNA will bound at A site of the ribosome. Then, peptide bond will be formed between these two amino acids on the both side. The old aminoacyl-tRNA will exit from the ribosome through E site and the new one will shift into the P site allowing another aminoacyl-tRNA to bound on A site. The formation of peptide bond is a continuous process thus it will be forming a chain of amino acids or known as polypeptide.
Lastly, chain termination will take place. After a long continuous process of formation of peptide bonds, eventually, the ribosomes reaching a point called as a stop codon. Stop codons does not have any tRNA thus there will be no aminoacyl-tRNA will be attached to its codon causing a disruption in the process. Formation of peptide bonds will stop and the old aminoacyl-tRNA will exit from the ribosome through E site. After that, all the ribosomal units will dissociate with the aid of release factors thus setting the polypeptide free to go. The newly synthesized polypeptide undergo posttranslational modification thus they will be modified before they reach their final form. The video below shows the whole process of translation.
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