Question

Explain the steps involved in translation.

Answer 1

Hint: Translation is the process of translating the sequence of m RNA (messenger RNA) into a sequence of amino acids. This translation takes place during protein synthesis. Here, the relationship between the sequence of base pairs and the corresponding amino acid(which encodes) describes the genetic code.

Complete answer:
This process involves the transport of amino acids to the ribosome, where they are assembled in the polypeptide chain. After which they will assemble into proteins somewhere in the cytoplasm. This process is accomplished by t RNA and occurs in several stages.

The major steps are given below:
1.Activation of amino acids: Here, when an amino acid(AA) and adenosine triphosphate(ATP), is mediated by aminoacyl synthetases enzyme, the enzyme complex AMP is formed.
2.Transfer of amino acid to transfer RNA: The enzyme complex above is reacted with the specific t RNA. As a result, an amino acid is transferred into t RNA and the enzyme and AMP are liberated.
3.Initiation of polypeptide chain: Now the charged transfer RNA shifts to the ribosome. In the presence of an initiation factor, it begins in the 5'-end of m RNA. The large and small are the two subunits of the ribosome. The m RNA binds to the small subunit and the large subunit bind to the small subunit to complete the initiation complex. The aminoacyl t RNA binding site(A site) and peptidyl site(P site) are the two sites of binding in large sub-units.
4. Elongation: The first codon m RNA binds with the anticodon of the methionyl t RNA complex in the P site. The other aminoacyl t RNA complex with the appropriate amino acids thus enters the ribosome and attaches to A site. The peptide bond is formed between the first and second amino acids when the anticodon binds to the second codon in the m RNA in the presence of an enzyme, peptidyl transferase.
Then, the translocation takes place i.e. when the first amino acids and the t RNA are broken, this t RNA is removed from the P site and the second t RNA from the A-side is pulled to the P site along with the m RNA.
5.Termination: The termination is signalled by one of the three-terminal codons-UAG, UGA, UAA. The polypeptide chain, t RNA, and m RNA are released after signalling and the ribosome subunits will be dissociated.

Note: Two classes of polyribosomes have been identified during protein translocation, free polyribosomes, and membrane-bound polyribosomes.