In the last step of the protein synthesis, the polypeptide chain is terminated by adequate termination signals (three special stop codons ) in the mRNA. Eventually, the completed chain separates from the ribosome. The release of the polypeptide-tRNA from the ribosome is initiated, when stop codon is reached, by a specific protein factor (release factor) which is attached to the ribosome and hydrolytically cleaves the ester bond between polypeptide and tRNS. Thereupon, the 70S-ribosome leaves the mRNA in free form. It can enter a new cycle if it first dissociates in its 50S and 30S subunits, for which one of the specific initiation factors is required.
Let's take a look at an example of biosynthesis to get a better understanding of this process. Proteins are a substance in the body made up of amino acid chains that join together by peptide bonds in a process called protein synthesis. There are 20 amino acids that make up the building blocks of proteins. Amino acids join together by peptide bonds to create chains of amino acids called polypeptide chains. The type of protein the body needs will dictate which amino acids are used in building these chains and how they are folded together to create a macromolecule.