Question

Describe the role played by tRNA in *translation* and in *polypeptide synthesis*?

Describe the role played by tRNA in translation and in polypeptide synthesis?

Answer 1

`tRNA` helps in bringing different amino acids to ribosome, the site of polypeptide synthesis, as per the sequence of codons in `mRNA`.

Explanation:

Translation is the synthesis of polypeptide on the surface of ribosome with specific sequence of amino acids as determined by codon sequence in DNA . There is a specific codon, made of one or more triplets, for each of the 20 amino acids, which are constituent of all proteins.

DNA directs polypeptide synthesis on the surface of ribosomes, located in the cytoplasm. DNA is located in the nucleus and does not move out of it. It synthesizes `mRNA` as per the sequence of codons in DNA. This process is termed transcription.

`mRNA` moves out of the nucleus and its initiating codon `AUG` gets attached to the acceptor site of ribosome. Prior to the synthesis of polypeptide, all the amino acids in the cytoplasmic pool get attached to their specific `tRNA`. The codon sequence in `tRNA` is complimentary to that of codon sequence in `mRNA`.

`AUG` is mRNA codon of methionine. `tRNA` that gets attached to methionine has codon `UAC` and thus methionine tRNA recognizes methionine mRNA codon on the acceptor site of ribosome and helps in transferring methionine to the ribosome.

`tRNAs` will thus help in transferring amino acids from the cytoplasm to the acceptor site of ribosome in the same sequence as `mRNA` codons will reach the acceptor site.

`tRNA` thus helps in translation by bringing aminoacids in the sequence as determined by genetic code in DNA .