Protein synthesis what is translation

Biology Expert. Regina Bailey is a board-certified registered nurse, science writer and educator. Updated August 21, Elongation: The ribosome moves along the mRNA molecule linking amino acids and forming a polypeptide chain. Termination: The ribosome reaches a stop codon, which terminates protein synthesis and releases the ribosome. Featured Video.

Cite this Article Format. Bailey, Regina. Translation: Making Protein Synthesis Possible. Ribosomes - The Protein Builders of a Cell. What Is a Peptide? Definition and Examples. Your Privacy Rights. To change or withdraw your consent choices for ThoughtCo. Christopher P. Austin, M. Featured Content. Introduction to Genomics. Translation of an mRNA molecule by the ribosome occurs in three stages: initiation, elongation, and termination. During initiation, the small ribosomal subunit binds to the start of the mRNA sequence.

Next, the large ribosomal subunit binds to form the complete initiation complex. During the elongation stage, the ribosome continues to translate each codon in turn. Each corresponding amino acid is added to the growing chain and linked via a bond called a peptide bond. Figure 2. In prokaryotes, multiple RNA polymerases can transcribe a single bacterial gene while numerous ribosomes concurrently translate the mRNA transcripts into polypeptides. In this way, a specific protein can rapidly reach a high concentration in the bacterial cell.

Bacterial species typically have between 60 and 90 types. Serving as adaptors, each tRNA type binds to a specific codon on the mRNA template and adds the corresponding amino acid to the polypeptide chain.

As the adaptor molecules of translation, it is surprising that tRNAs can fit so much specificity into such a small package. Mature tRNAs take on a three-dimensional structure when complementary bases exposed in the single-stranded RNA molecule hydrogen bond with each other Figure 3.

The anticodon is a three-nucleotide sequence that bonds with an mRNA codon through complementary base pairing. At least one type of aminoacyl tRNA synthetase exists for each of the 20 amino acids. Figure 3. Translation is similar in prokaryotes and eukaryotes. Here we will explore how translation occurs in E. The initiation of protein synthesis begins with the formation of an initiation complex.

Because of its involvement in initiation, fMet is inserted at the beginning N terminus of every polypeptide chain synthesized by E. This interaction anchors the 30S ribosomal subunit at the correct location on the mRNA template. At this point, the 50S ribosomal subunit then binds to the initiation complex, forming an intact ribosome.

Figure 4. Translation in bacteria begins with the formation of the initiation complex, which includes the small ribosomal subunit, the mRNA, the initiator tRNA carrying N-formyl-methionine, and initiation factors. Then the 50S subunit binds, forming an intact ribosome. In prokaryotes and eukaryotes, the basics of elongation of translation are the same. The P peptidyl site binds charged tRNAs carrying amino acids that have formed peptide bonds with the growing polypeptide chain but have not yet dissociated from their corresponding tRNA.

The E exit site releases dissociated tRNAs so that they can be recharged with free amino acids. Elongation proceeds with single-codon movements of the ribosome each called a translocation event. During each translocation event, the charged tRNAs enter at the A site, then shift to the P site, and then finally to the E site for removal.

Peptide bonds form between the amino group of the amino acid attached to the A-site tRNA and the carboxyl group of the amino acid attached to the P-site tRNA. The formation of each peptide bond is catalyzed by peptidyl transferase , an RNA-based ribozyme that is integrated into the 50S ribosomal subunit. The amino acid bound to the P-site tRNA is also linked to the growing polypeptide chain.

Several of the steps during elongation, including binding of a charged aminoacyl tRNA to the A site and translocation, require energy derived from GTP hydrolysis, which is catalyzed by specific elongation factors.

Amazingly, the E. On aligning with the A site, these nonsense codons are recognized by release factors in prokaryotes and eukaryotes that result in the P-site amino acid detaching from its tRNA, releasing the newly made polypeptide.