Select the correct statement regarding protein synthesis `:`

Options

A. When the small subunit of the ribosome encounters an mRNA the process of translation begins
B. Peptidase catalyses the formation of peptide bond
C. UTRs are present between the start and stop codon
D. At the end of translation the releases factor binds to the initiation codon

Answer

To solve the question regarding protein synthesis, we need to analyze the provided statements and determine which one is correct. Here’s a step-by-step breakdown:

### Step 1: Understand the Role of Ribosomes in Translation
- Ribosomes are the cellular machinery responsible for protein synthesis. They consist of two subunits: a small subunit and a large subunit.
- The small subunit of the ribosome binds to the mRNA (messenger RNA) during the initiation of translation.

**Hint for Step 1:** Recall the structure of ribosomes and their function in translation.

### Step 2: Analyze the First Statement
- The first statement claims that the small subunit of the ribosome encounters the mRNA and that the process of translation begins.
- This statement is accurate because the small subunit does indeed bind to the mRNA, which is the first step in the translation process.

**Hint for Step 2:** Think about what happens first in the translation process.

### Step 3: Evaluate the Second Statement
- The second statement suggests that peptide bonds are catalyzed by "peptide" (likely a typo for "peptidyl") and is incorrect.
- In reality, the formation of peptide bonds during translation is catalyzed by the enzyme peptidyl transferase, which is part of the ribosome's large subunit.

**Hint for Step 3:** Remember the specific enzymes involved in peptide bond formation.

### Step 4: Assess the Third Statement
- The third statement mentions that UTRs (untranslated regions) are present between the start and stop codons.
- This statement is incorrect because UTRs are located at the 5' and 3' ends of the mRNA, not between the start and stop codons.

**Hint for Step 4:** Recall the location and function of UTRs in mRNA.

### Step 5: Review the Fourth Statement
- The fourth statement claims that at the end of translation, the release factor binds to the initiation codon.
- This is incorrect as the release factor binds to the stop codon, not the initiation codon, to terminate translation.

**Hint for Step 5:** Identify the role of release factors in the translation process.

### Conclusion
After analyzing all the statements, we conclude that the first statement is the only correct one regarding protein synthesis.

### Final Answer
The correct statement regarding protein synthesis is: **The small subunit of the ribosome encounters the mRNA, and the process of translation begins.**