Arrange the following steps in the process of translation in correct sequence?
(A) Binding of release factor to stop codon
(B) Movement of ribosome from codon to codon along mRNA
(C) Aminoacylation of tRNA
(D) Binding of ribosome to mRNA at AUG
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (C), (D), (B), (A)
(C) Aminoacylation of tRNA — first. Each amino acid is activated and joined to its tRNA (charging of tRNA) before translation starts.
(D) Binding of ribosome to mRNA at AUG — second. The ribosome binds the mRNA at the start codon AUG, recognised by the initiator tRNA.
(B) Movement of ribosome from codon to codon along mRNA — third. In elongation, the ribosome moves along the mRNA, adding amino acids one by one.
(A) Binding of release factor to stop codon — last. A release factor binds the stop codon, ending translation and releasing the polypeptide.
NCERT Extract:
Translation – “… For initiation, the ribosome binds to the mRNA at the start codon (AUG) that is recognised only by the initiator tRNA. The ribosome proceeds to the elongation phase of protein synthesis. During this stage, complexes composed of an amino acid linked to tRNA, sequentially bind to the appropriate codon in mRNA by forming complementary base pairs with the tRNA anticodon. The ribosome moves from codon to codon along the mRNA. Amino acids are added one by one, translated into Polypeptide sequences dictated by DNA and represented by mRNA. At the end, a release factor binds to the stop codon, terminating translation and releasing the complete polypeptide from the ribosome.”