Where and how does protein biosynthesis occur?
In the cytoplasm, there is a process of protein synthesis, which is also called translation. Translation is the translation of the nucleotide sequence of an mRNA molecule into the amino acid sequence of a protein molecule. The ribosome interacts with the end of the mRNA from which protein synthesis should begin. In this case, the beginning of the future protein is indicated by the AUG triplet, which is a sign of the beginning of translation. Since this codon encodes the amino acid methionine, all proteins (except in special cases) begin with methionine. After binding, the ribosome begins to move along the mRNA, lingering on each of its sites, which includes two codons (i.e. 3 + 3 = 6 nucleotides). The delay time is only 0.2 s. During this time, the tRNA molecule, the anticodon of which is complementary to the codon located in the ribosome, manages to recognize it. The amino acid that has been linked to this tRNA is separated from the “petiole” and attached to form a peptide bond to the growing protein chain. At the same moment, the next tRNA approaches the ribosome, the anticodon of which is complementary to the next triplet in the mRNA, and the next amino acid brought by this tRNA is included in the growing chain. After this, the ribosome is shifted by mRNA, delayed by the following nucleotides, and everything is repeated again.
