Approximately how many restriction enzymes have been isolated from the different (over 230) strains of bacteria:

Options

A. 300
B. 600
C. 750
D. 900

Answer

To answer the question regarding the number of restriction enzymes isolated from over 230 strains of bacteria, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Restriction Enzymes**:
- Restriction enzymes, also known as restriction endonucleases, are proteins that cut DNA at specific sequences. They play a crucial role in molecular biology, particularly in recombinant DNA technology.

2. **Researching the Source**:
- These enzymes are primarily found in bacteria, where they serve as a defense mechanism against foreign DNA, such as that from viruses.

3. **Identifying the Number of Enzymes**:
- It is known that a significant number of restriction enzymes have been isolated from various bacterial strains.

4. **Analyzing the Options**:
- The question provides four options regarding the number of restriction enzymes:
- Option A: 300
- Option B: 600
- Option C: Not specified
- Option D: 900

5. **Selecting the Correct Answer**:
- Based on the information available, it is established that over 900 restriction enzymes have been isolated from more than 230 strains of bacteria. Therefore, the correct answer is **Option D: 900**.

### Final Answer:
Approximately 900 restriction enzymes have been isolated from over 230 strains of bacteria.

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