Introduction:

The molecular basis of translation is the process by which the genetic information stored in RNA is converted into a functional protein. This process occurs on ribosomes, which are large complexes of proteins and RNA molecules.

Initiation:

The first step in translation is the initiation of protein synthesis. This process is mediated by a complex of proteins called the initiation factors, which help to position the ribosome at the start site of translation and to recruit the first aminoacyl-tRNA (charged tRNA molecule with an amino acid attached) to the ribosome. The process of initiation starts with the recruitment of the small subunit of the ribosome to the 5′ end of the mRNA. The small ribosomal subunit binds to the cap structure at the 5′ end of the mRNA and scans along the mRNA looking for an AUG start codon, which is the codon that codes for methionine, the first amino acid in the protein.

Elongation:

Once the ribosome is positioned at the start site of translation, it begins to add amino acids to the growing protein chain. The process of elongation is mediated by a complex of proteins called the elongation factors. The ribosome moves along the mRNA, adding one amino acid at a time to the growing protein chain. Each amino acid is added to the growing chain by a specific tRNA molecule that carries the corresponding amino acid. The tRNA molecule is recognized by the ribosome by the anticodon, a three-base sequence that is complementary to the codon on the mRNA. The ribosome brings the tRNA molecule in a specific orientation and the correct amino acid is added to the growing peptide chain.

Termination:

Once the ribosome reaches a stop codon, which is a sequence of three bases that does not code for an amino acid, translation is terminated. The stop codon signals the release of the newly synthesized protein from the ribosome. Release factors bind to the stop codon and catalyze the hydrolysis of the peptidyl-tRNA bond, releasing the newly synthesized protein from the ribosome.

Post-translational modifications:

After translation, the newly synthesized protein undergoes a series of post-translational modifications such as folding, cleavage, phosphorylation, and glycosylation. These modifications are important for the stability and function of the protein.

In summary, the molecular basis of translation is a complex process that involves the interaction of several proteins and RNA molecules. The process starts with initiation, where the ribosome is positioned at the start site of translation, and then proceeds with the elongation, where the ribosome moves along the mRNA adding one amino acid at a time to the growing protein chain. The process ends with termination, where the newly synthesized protein is released from the ribosome and goes through post-translational modifications that are important for its stability and function.