How many fragments will be generated if you digest a linear DNA molecule with a restriction enzyme having four recongnition sites on the DNA?

Options

A. 3
B. 6
C. 5
D. 4

Explanation

To determine how many fragments will be generated when a linear DNA molecule is digested with a restriction enzyme that has four recognition sites, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Linear DNA Structure**:
- A linear DNA molecule is a continuous strand of DNA with two ends. It can be visualized as a straight line.

2. **Identifying Recognition Sites**:
- The problem states that there are four recognition sites (RS) on the linear DNA. Each recognition site is a specific sequence where the restriction enzyme will cut the DNA.

3. **Counting the Cuts**:
- When the restriction enzyme recognizes and cuts at each of the four recognition sites, it will create a break in the DNA strand.

4. **Determining the Number of Fragments**:
- Each cut made by the restriction enzyme divides the DNA into separate fragments.
- If there are 'n' cuts made, the number of fragments generated is given by the formula:
\[ \text{Number of fragments} = n + 1 \]
- In this case, since there are 4 recognition sites, the restriction enzyme will make 4 cuts.

5. **Applying the Formula**:
- Using the formula:
\[ \text{Number of fragments} = 4 + 1 = 5 \]

6. **Conclusion**:
- Therefore, when a linear DNA molecule is digested with a restriction enzyme that has four recognition sites, it will generate a total of 5 fragments.

### Final Answer:
The number of fragments generated is **5**.

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