Answer :

Translation is the decoding of m-RNA to form amino acid chain with the help of ribosome in the cytosol of the cell.

Molecules Involved In Translation:

1. Amino acids: These are the structural unit of proteins which are joined together to form a protein chain.

2. m-RNA: The m-RNA or messenger RNA has codons, each codon codes for one amino acid.

3. t-RNA: The t-RNA or transfer RNA binds with amino acid carrier and carry the amino acid sequence.

4. Ribosome: These are required for the catalysis of the process.

Steps Involved In Translation:


1. At the 5’ end of the m-RNA the smaller 40S subunit of the ribosome with methionyl-tRNA scans the m-RNA to find the start codon (5’AUG).

2.This codon (AUG) is specific to methionine.

3.Now, the larger 60S subunit of the ribosome binds to the m-RNA.This 60S ribosomal subunit has two t-RNA binding sites.

Site P: This site can hold the peptide chain.

Site A: This site can hold the t-RNA.


1. Now, as the Met-tRNA binds to the P site of the 60S subunit of the RNA. Another aminoacyl- tRNA which has an anticodon complementary to the next codon occupies the site A within the 60S subunit of ribosome.

2. The enzyme peptidyl transferase forms a peptide bond between Methionyl-tRNA and Aminoacyl-tRNA.

3. This makes the t-RNA molecule at the P site to become uncharged and it leaves the ribosome.

4. The ribosome moves along the m-RNA molecule to the next codon which opens the Site A for next aminoacyl-tRNA.

5. The polypeptide chain is built in the direction of N to C terminal.


1. Now, as the A site is vacant the stop codon enters the site.

2. None of the t-RNA molecule binds to this codon.

3.The peptide bond of Methionyl-tRNA and Aminoacyl-tRNA become hydrolysed releasing the polypeptide into the cytoplasm.

4. The ribosomal subunit now disassociates.

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What is aminoacylBiology - Board Papers