After the addition of the last amino acid to a growing polypeptide chain during the process of protein synthesis, one of the termination codons reaches the appropriate site on the ribosomal surface and then the following envents take place
(i) Release of t-RNA molecule from the ribosome.
(ii) Dislodging of polypeptide chain from the t-RNA
(iii) Dissociation of ribosomes into large and small subunits. ltBrgt The correct sequence of these events:

Options

A. (i),(ii),(iii)
B. (iii),(ii),(i)
C. (ii),(i),(iii)
D. (iii),(i),(iii)

Answer

To determine the correct sequence of events that occur after the addition of the last amino acid to a growing polypeptide chain during protein synthesis, we need to analyze the process of termination in translation. Here are the steps involved:

### Step-by-Step Solution:

1. **Dissociation of Ribosomes into Large and Small Subunits**:
- When a termination codon reaches the A site of the ribosome, release factors bind to the ribosome. This binding triggers the dissociation of the ribosomal subunits (the large subunit and the small subunit separate from each other).

2. **Dislodging of Polypeptide Chain from the tRNA**:
- Following the dissociation of the ribosomal subunits, the release factors facilitate the release of the completed polypeptide chain from the tRNA that was in the P site of the ribosome. This step is crucial as it allows the newly synthesized protein to be released into the cellular environment.

3. **Release of tRNA Molecule from the Ribosome**:
- Finally, the tRNA molecule that was carrying the last amino acid is released from the ribosome. This step occurs after the polypeptide chain has been dislodged and is the last event in the termination process.

### Correct Sequence of Events:
- **(iii) Dissociation of ribosomes into large and small subunits**
- **(ii) Dislodging of polypeptide chain from the tRNA**
- **(i) Release of tRNA molecule from the ribosome**

Thus, the correct sequence of these events is: **(iii) → (ii) → (i)**.