If the base sequence of a codon in mRNA is `5'-AUG-3'`, the sequence of tRNA pairing with it must be

Options

A. 5'- UAC- 3'
B. 5'-CAU-3'
C. 5'-AUG-3'
D. 5'-GUA-3'

Answer

To determine the sequence of tRNA that pairs with the mRNA codon `5'-AUG-3'`, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the mRNA Codon**:
The given codon in mRNA is `5'-AUG-3'`.

2. **Determine the Anticodon**:
The tRNA anticodon will be complementary to the mRNA codon. To find the anticodon, we need to convert the mRNA codon from the 5' to 3' direction to the corresponding base pairs:
- A (Adenine) pairs with U (Uracil)
- U (Uracil) pairs with A (Adenine)
- G (Guanine) pairs with C (Cytosine)

Therefore, the complementary bases for `AUG` will be:
- A → U
- U → A
- G → C

This gives us the sequence `3'-UAC-5'` for the anticodon.

3. **Convert Anticodon to 5' to 3' Direction**:
Since the tRNA anticodon is typically written in the 5' to 3' direction for clarity, we need to reverse the sequence `3'-UAC-5'` to `5'-CAU-3'`.

4. **Final Answer**:
Thus, the sequence of tRNA that pairs with the mRNA codon `5'-AUG-3'` is `5'-CAU-3'`.

### Summary:
The tRNA sequence that pairs with the mRNA codon `5'-AUG-3'` is `5'-CAU-3'`.

---