Page 100 - Medicinal Plants_PharmD general

7. A peptide bond is established between the carboxylic and amino group
of the two amino acids in the presence of the enzyme peptide synthetase.
The previous tRNA-amino acid complex breaks so that the tRNA
molecule is released into the cytoplasm to become charged again with
amino acid.

8. In the same way, during the movement of the m-RNA and ribosome, a
number of specific amino acids are added one after another into the
growing polypeptide chain.

Protein synthesis in ribosome
9. Termination of the polypeptide chain takes place when ribosome (to

which the polypeptide chain is attached) comes over the non-sense
codon in mRNA molecule during its movement against mRNA. Non-
sense or chain termination codons are UAA, UAG, and UGA.
10. After formation of polypeptide chains the mRNA disintegrates and
ribosome again dissociates into its subunits (plants possess 80S
ribosome made up of a large 60S and a small 40S ribosome subunits)
which are cycled back into the cytoplasm.

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