ACTIVATION OF AMINO ACIDS AND ELONGATION OF THE POLYPEPTIDE CHAIN IN PROKARYOTES

Prokaryotes, such as bacteria, have a unique process of protein synthesis compared to eukaryotes, such as humans. The process of protein synthesis in prokaryotes involves the activation of amino acids, the formation of an initiation complex, and the elongation of the polypeptide chain.

Activation of Amino Acids:

In prokaryotes, the first step in protein synthesis is the activation of amino acids. This is done by the enzyme aminoacyl-tRNA synthetase, which attaches an amino group to the appropriate tRNA molecule. There are 20 different tRNA molecules in prokaryotes, each specific to a particular amino acid. The aminoacyl-tRNA synthetase enzyme recognizes the appropriate tRNA molecule based on its anticodon, and attaches the amino group to the tRNA molecule.

Formation of Initiation Complex:

Once the amino acids are activated, the next step is the formation of the initiation complex. This complex is formed when the small subunit of the ribosome binds to the messenger RNA (mRNA) molecule and recognizes the start codon (AUG). The start codon is the first codon in the mRNA molecule that is read by the ribosome, and it signals the beginning of protein synthesis. The small subunit of the ribosome then recruits the large subunit of the ribosome, and the initiation complex is formed.

Elongation of the Polypeptide Chain:

Once the initiation complex is formed, the elongation of the polypeptide chain begins. The ribosome reads the mRNA molecule codon by codon, and each codon specifies a particular amino acid. The aminoacyl-tRNA synthetase enzyme then brings the appropriate amino acid to the ribosome, and it is added to the growing polypeptide chain. This process is repeated until the end of the mRNA molecule is reached, at which point the polypeptide chain is released.

In prokaryotes, the elongation of the polypeptide chain is a continuous process, with the ribosome reading the mRNA molecule in a continuous manner. This is in contrast to eukaryotes, where the elongation of the polypeptide chain is divided into three stages: initiation, elongation, and termination.