mechanisms of translation in prokaryotes Part 1 PRESENTED

mechanisms of translation in prokaryotes (Part -1) PRESENTED BY: SANIA TAHRIM DEPARTMENT OF ZOOLOGY KARIM CITY COLLEGE, JAMSHEDPUR U. G Sem 6 , CC – 13

Prokaryotic Translation �Translation is similar in prokaryotes and eukaryotes. �Here we will explore how translation occurs in E. coli, a representative prokaryote, and specify any differences between bacterial and eukaryotic translation.

Mechanism of Translation in Prokaryotes: �Translation process consists of three major phases or stages: �(1) Initiation �(2) Elongation and �(3) Termination.

Initiation �The initiation of protein synthesis begins with the formation of an initiation complex. �In E. coli, this complex involves the small 30 S ribosome, the m. RNA template, three initiation factors that help the ribosome assemble correctly, guanosine triphosphate (GTP) that acts as an energy source, and a special initiator t. RNA carrying N-formylmethionine (f. Met-t. RNAf. Met)

Initiation �The initiator t. RNA interacts with the start codon AUG of the m. RNA and carries a formylated methionine (f. Met). Because of its involvement in initiation, f. Met is inserted at the beginning (N terminus) of every polypeptide chain synthesized by E. coli.

Initiation �In E. coli m. RNA, a leader sequence upstream of the first AUG codon, called the Shine-Dalgarno sequence (also known as the ribosomal binding site AGGAGG), interacts through complementary base pairing with the r. RNA molecules that compose the ribosome.

Initiation �This interaction anchors the 30 S ribosomal subunit at the correct location on the m. RNA template. � At this point, the 50 S ribosomal subunit then binds to the initiation complex, forming an intact ribosome.

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