The natural function of a restriction enzymes is to

Options

A. cut foreign DNA
B. remove introns from the RNA transcript
C. remove exons from the RNA transcript
D. facilitate m-RNA formation from nucleotides

Answer

**Step-by-Step Solution:**

1. **Understanding Restriction Enzymes**: Begin by recognizing what restriction enzymes are. They are proteins that act as molecular scissors to cut DNA at specific sequences.

2. **Analyzing the Options**: The question provides four options regarding the natural function of restriction enzymes. We need to evaluate each option to identify the correct one.

3. **Evaluating Option 1 - Cut Foreign DNA**: This option states that the natural function of restriction enzymes is to cut foreign DNA. This is indeed correct, as restriction enzymes are primarily used by bacteria to defend against invading viruses (bacteriophages) by cutting their DNA.

4. **Evaluating Option 2 - Remove Introns from RNA Transcript**: This option suggests that restriction enzymes remove introns from RNA transcripts. However, this process is performed by a complex called the spliceosome, not by restriction enzymes.

5. **Evaluating Option 3 - Remove Exons from RNA Transcript**: Similar to option 2, this option is incorrect as restriction enzymes do not remove exons. Exons are retained in the RNA after splicing.

6. **Evaluating Option 4 - Facilitate mRNA Formation from Nucleotides**: This option implies that restriction enzymes facilitate mRNA formation. However, this process is carried out by RNA polymerase, not restriction enzymes.

7. **Conclusion**: After evaluating all options, the correct answer is that the natural function of a restriction enzyme is to cut foreign DNA.

**Final Answer**: The natural function of a restriction enzyme is to cut foreign DNA.

---