Which one of the following pairs of codons is correctly matched with their function or the signal for the particular amino acid?

Options

A. GUU, GCU-Alanine
B. UAG, UGA-stop
C. AUG, ACG-Start/methionine
D. UUA, UCA-Leucine

Explanation

To solve the question of which pair of codons is correctly matched with their function or signal for a particular amino acid, we will analyze each option provided.

### Step-by-Step Solution:

1. **Understand Codons**: Codons are sequences of three nucleotides in mRNA that correspond to specific amino acids or signals during protein synthesis.

2. **Identify the Options**: The options given are:
- A) GUU, GCU - Alanine
- B) UAG, UGA - Stop
- C) AUG, ACG - Start, Methionine
- D) UUA, UCA - Leucine

3. **Evaluate Each Option**:
- **Option A (GUU, GCU - Alanine)**:
- GUU codes for Valine, not Alanine.
- GCU codes for Alanine.
- Therefore, this pair is incorrect.

- **Option B (UAG, UGA - Stop)**:
- UAG is a stop codon.
- UGA is also a stop codon.
- This pair is correctly matched as both are stop signals.

- **Option C (AUG, ACG - Start, Methionine)**:
- AUG is the start codon and codes for Methionine.
- ACG codes for Threonine, not a start signal.
- Therefore, this pair is incorrect.

- **Option D (UUA, UCA - Leucine)**:
- UUA codes for Leucine.
- UCA codes for Serine, not Leucine.
- Therefore, this pair is incorrect.

4. **Conclusion**: The only correct pair is **Option B (UAG, UGA - Stop)**.

### Final Answer:
The correct pair of codons matched with their function is **B) UAG, UGA - Stop**.