Question

Arrange different stages of protein synthesis :
A. A specific Amino Acid initiates protein synthesis
B. Aminoacyl-tRNA synthetases attach the correct Amino Acids to their tRNAs
C. Termination of polypeptide synthesis requires a special signal
D. Peptide bonds are formed in the elongation stage
E. Newly synthesized polypeptide chains undergo folding and processing
Choose the correct answer from the options given below :

• A. A, B, C, D, E
• B. C, B, A, D, E
• C. D, B, A, C, E
• D. B, A, D, C, E

Hint:

Translation steps mirror reading a book: Get your materials ready (charging tRNA), open the book (Initiation), read page by page (Elongation), reach the end (Termination), and then understand the plot (Folding into functional protein).

Answer 1

The Correct Option is D

Step 1: Concept:
The question asks for the proper sequential timeline of molecular events that occur during cellular translation (protein synthesis).

Step 2: Step-by-step Explanation:

•

Step 1: Activation of Amino Acids (B) - Before translation on the ribosome can even begin, the transfer RNA (tRNA) molecules must be "charged" with their appropriate amino acids. This crucial preparatory step is catalyzed by specific enzymes called aminoacyl-tRNA synthetases in the cytoplasm.

•

Step 2: Initiation (A) - The actual ribosomal synthesis begins when the small ribosomal subunit binds to the mRNA. The process is always initiated by a specific amino acid dictated by the start codon (usually AUG, coding for Methionine in eukaryotes or formyl-methionine in prokaryotes).

•

Step 3: Elongation (D) - Once the initiation complex is fully assembled, the ribosome translocates along the mRNA. The enzyme peptidyl transferase iteratively catalyzes the formation of peptide bonds between sequentially delivered amino acids, actively elongating the growing polypeptide chain.

•

Step 4: Termination (C) - Elongation continues continuously until the ribosome encounters a "special signal"—specifically, a nonsense/stop codon (UAA, UAG, or UGA) positioned in the mRNA sequence. Release factors bind, forcing the ribosome to dissemble and release the newly completed raw polypeptide chain.

•

Step 5: Post-translational modifications (E) - A linear chain of amino acids is rarely functional immediately. The newly synthesized, nascent polypeptide chain must undergo spontaneous or chaperone-mediated 3D folding and potentially other chemical processing (like glycosylation or cleavage) in the ER/Golgi to achieve its final, functional conformation.

• Therefore, the strictly ordered chronological sequence of events is B \(\rightarrow\) A \(\rightarrow\) D \(\rightarrow\) C \(\rightarrow\) E.

Step 3: Final Answer:
Option (D) accurately represents the biological sequence of translation.