Purchase a license to download a nonwatermarked version of this video on AlilaMedicalMedia(dot)com

Check out our new Alila Academy AlilaAcademy(dot)com complete video courses with quizzes, PDFs, and downloadable images.

©Alila Medical Media. All rights reserved.

The translation process involves the following components:
mRNA or messenger RNA containing the genetic information to be translated.
tRNA or transfer RNA bringing in the amino acids – the building blocks of the protein.
Ribosome – the machine that performs the translation. The ribosome has two subunits: small and large.
Several initiation factors, elongation factors, and release factors. These factors assist with initiation, elongation and termination of the process, respectively.
Steps of the translation process:
Initiation (eukaryotes) : The small ribosomal subunit binds to the initiator tRNA carrying the initiator amino acid methionine. This complex then attaches to the cap structure at the 5’ end of an mRNA and scans for the start codon AUG. The process is mediated by several initiation factors. At the start codon, the large ribosomal subunit joins the complex and all initiation factors are released. The ribosome has three sites: the Asite is the entry site for new tRNA charged with aminoacid or aminoacyltRNA; the Psite is occupied by peptidyltRNA the tRNA that carries the growing polypeptide chain; the Esite is the exit site for the tRNA after it’s done delivering the amino acid. The initiator tRNA is positioned in the Psite.
Elongation: A new tRNA carrying an amino acid enters the Asite of the ribosome. On the ribosome, the anticodon of the incoming tRNA is matched against the mRNA codon positioned in the Asite. During this proofreading, tRNA with incorrect anticodons are rejected and replaced by new tRNA that are again checked. When the right aminoacyltRNA enters the Asite, a peptide bond is made between the two nowadjacent aminoacids. As the peptide bond is formed, the tRNA in the Psite releases the aminoacids onto the tRNA in the Asite and becomes empty. At the same time, the ribosome moves one triplet forward on the mRNA. As a result, the empty tRNA is now in the Esite and the peptidyl tRNA is in the Psite. The Asite is now unoccupied and is ready to accept a new tRNA. The cycle is repeated for each codon on the mRNA.
Termination: Termination happens when one of the three stop codons is positioned in the Asite. No tRNA can fit in the Asite at that point as there are no tRNA that match the sequence. Instead, these codons are recognized by a protein, a release factor. Binding of the release factor catalyzes the cleavage of the bond between the polypeptide and the tRNA. The polypeptide is released from the ribosome. The ribosome is disassociated into subunits and is ready for a new round of translation. The newly made polypeptide usually requires additional modifications and folding before it can become an active protein.