Translation process: Elongation ( with step by step description)

In the previous lecture we discussed about the translation initiation process now its time to describe about the elongation and termination process, actually this processes are really very interesting , so lets see...

Elongation:

Ribosomal subunit has 3 site A site that’s the entry site of new charged with amino acyl l tRNA P site is occupied by peptydal tRNA that tRNA carries the peptydal polypeptide chain of amino acids that will finale produce protein by folding mechanism.After leaving the amino acid to P site E site is the exit site.

New tRNA with amino acid containing codon will come and bind with the A site, first you have to ensure that mRNA has the complementary against the new tRNA coading sequence, if not matched that will be rejected and new tRNA will come and if matched that will bind with the mRNA at the A site.

Peptide bond will be formed with the new adjacent amino acid with the previous one.In this step EFTU enzyme will help to do this movement with the energy source GTP.

Now the most interesting things will happen, now tRNA of the p site will release amino acid to the tRNA of A site and they will replace themselves , tRNA of P site will go to the E site and t RNA of A site will come to the P site just one sliding of the tRNA. As a result now A site will be free!

 I hope you marked that as the ribosomal subunit going throug the 5'-3' stop codon is just visible  3 codon nearby the start codon, stop codon is not moving just full ribosomal subunit is going through the stop codon  as distance is shortening.

This process will continue thoroughly until the ribosomal subunit reach the stop codon, and amino acids of tRNA will attach at the p site and create a large chain.And all the time EFTU enzyme helps to pass the tRNA to A site of the ribosomal subunit.This chain will finally turn  into protein by folding mechanism.

finally it ribosomal subunit pass to the stop codon and now its time to stop this process of altering and adding amino acids. In the mean time a long chain of amino acids are binded with peptide bond.

In the last picture you see the result.its the ending of elongation and time to start termination stage!! see the termination stage in the next lecture...thanks!