How many fragments will be generated if you digest a linear DNA molecule with a restriction enzyme having four recognition sites on the DNA?
(a) 3
(b) 6
(c) 5
(d) 4

Explanation

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

### Step-by-Step Solution:

1. **Understand the Structure of Linear DNA**:
- A linear DNA molecule has two ends and can be visualized as a straight line.

2. **Identify the Recognition Sites**:
- The problem states that there are four recognition sites on the DNA molecule. These sites are where the restriction enzyme will cut the DNA.

3. **Determine the Number of Cuts**:
- Each recognition site corresponds to a cut made by the restriction enzyme. Therefore, if there are four recognition sites, the enzyme will make four cuts.

4. **Calculate the Number of Fragments**:
- The number of fragments generated from a linear DNA molecule can be calculated using the formula:
\[ \text{Number of fragments} = \text{Number of cuts} + 1 \]
- In this case, with four cuts:
\[ \text{Number of fragments} = 4 + 1 = 5 \]

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

### Final Answer:
(c) 5

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