• (A) Elongation
• (B) Release of polypeptide
• (C) Initiation
• (D) Folding of the polypeptide
• (E) Termination

Choose the correct answer from the options given below:

1. (B), (C), (D), (A), (E)
2. (A), (D), (E), (C), (B)
3. (C), (A), (E), (B), (D)
4. (A), (B), (C), (D), (E)

   E. coli translation follows a precise sequence: initiation assembles the ribosome-mRNA-tRNA complex, elongation adds amino acids, termination releases the polypeptide upon stop codon recognition, and folding occurs post-release as a spontaneous or chaperoned process.

   Correct Answer

   (C), (A), (E), (B), (D).

   Step Analysis

   (A) Elongation: Amino acids are sequentially added to the growing polypeptide chain via peptidyl transferase and translocation (EF-Tu, EF-G), following initiation.

   (B) Release of polypeptide: The completed chain is freed from the ribosome during termination by release factors (RF1/RF2 recognize stop codons, RF3 aids dissociation).

   (C) Initiation: The 30S subunit binds mRNA at Shine-Dalgarno sequence, fMet-tRNA pairs with AUG start codon, and 50S subunit joins (IF1-3, GTP required).

   (D) Folding of the polypeptide: Occurs after release in the cytosol; primary sequence folds into secondary/tertiary structures via hydrogen bonds, chaperones (e.g., GroEL), or disulfide bridges.

   (E) Termination: Ribosome reaches UAA/UGA/UAG stop codon; RFs hydrolyze the ester bond, releasing the polypeptide and dissociating subunits.

   Option Breakdown

   • (B), (C), (D), (A), (E): Incorrect; starts with release (post-termination) and misorders core steps.

   • (A), (D), (E), (C), (B): Incorrect; begins with elongation before initiation.

   • (C), (A), (E), (B), (D): Correct; standard ribosomal sequence: initiation → elongation → termination → release → folding.

   • (A), (B), (C), (D), (E): Incorrect; elongation precedes initiation.

   E coli translation steps sequentially convert mRNA to functional proteins on ribosomes, vital for prokaryotic gene expression.

   Core Ribosomal Phases

   Initiation (C) assembles the complex at AUG. Elongation (A) cycles A/P/E sites for chain growth. Termination (E) halts at stop codons, enabling polypeptide release (B).

   Post-Translational Step

   Folding (D) follows release, achieving native conformation.​

   Step	Order & Role
   (C) Initiation	Ribosome assembly
   (A) Elongation	Amino acid addition
   (E) Termination	Stop codon recognition
   (B) Release	Polypeptide ejection
   (D) Folding	3D structure formation

   This sequence underpins antibiotic targets like tetracycline (blocks A site). For exams, note folding as final.​