In E.coli, which of the following codons are recognized by the release factor `RF_1`?

Options

A. UAG and UGA
B. UAA and UGG
C. UAG and UAA
D. UAG and UUA

Answer

To solve the question regarding which codons are recognized by the release factor RF1 in E. coli, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Role of Release Factors**:
- Release factors are proteins that recognize stop codons during the process of translation termination in protein synthesis.

2. **Identify the Release Factors in E. coli**:
- In E. coli, there are two main release factors: RF1 and RF2.
- RF1 recognizes two specific stop codons, while RF2 recognizes different ones.

3. **List the Stop Codons**:
- The three stop codons in the genetic code are:
- UAA
- UAG
- UGA

4. **Determine the Codons Recognized by RF1**:
- RF1 specifically recognizes the codons UAA and UAG.
- RF2 recognizes UGA and UAA.

5. **Analyze the Options Provided**:
- Option A: UAG and UGA (Incorrect, as UGA is recognized by RF2)
- Option B: UAA and UGG (Incorrect, as UGG is not a stop codon)
- Option C: UAG and UAA (Correct, as both UAA and UAG are recognized by RF1)
- Option D: UAG (Incorrect, as it does not include UAA)

6. **Select the Correct Answer**:
- The correct answer is **Option C: UAG and UAA**.

### Final Answer:
The codons recognized by the release factor RF1 in E. coli are **UAA and UAG** (Option C).