When cut by the same restriction enzyme, the resultant DNA fragments have the same kind of sticky-ends and these can be joined together (end to end) using

Options

A. ATP
B. DNA ligase
C. DNA polymerases
D. restriction enzymes

Answer

To solve the question, we need to understand the process of joining DNA fragments that have been cut by the same restriction enzyme, resulting in the same kind of sticky ends. Here’s a step-by-step breakdown of the solution:

### Step-by-Step Solution:

1. **Understanding Restriction Enzymes**:
- Restriction enzymes are proteins that cut DNA at specific sequences. When DNA is cut by the same restriction enzyme, it produces fragments with complementary sticky ends.

2. **Sticky Ends**:
- Sticky ends are short single-stranded overhangs at the ends of the DNA fragments. These overhangs can base-pair with complementary sequences on other DNA fragments that have been cut by the same enzyme.

3. **Joining DNA Fragments**:
- To join these DNA fragments together, we need an enzyme that can facilitate the joining process. This is where DNA ligase comes into play.

4. **Role of DNA Ligase**:
- DNA ligase is an enzyme that catalyzes the formation of phosphodiester bonds between the sugar-phosphate backbone of the DNA strands. This process effectively seals the nicks in the DNA backbone, joining the fragments end to end.

5. **Evaluating Options**:
- The question provides several options for the enzyme that can join the DNA fragments:
- **Option A**: ATP - Incorrect, as ATP is not an enzyme but an energy molecule.
- **Option B**: DNA ligase - Correct, as it is the enzyme that joins DNA fragments.
- **Option C**: DNA polymerase - Incorrect, as it is involved in DNA synthesis, not joining fragments.
- **Option D**: Restriction enzymes - Incorrect, as they are used for cutting DNA, not joining it.

6. **Conclusion**:
- The correct answer to the question is **DNA ligase**, as it is the enzyme responsible for joining DNA fragments with the same sticky ends.

### Final Answer:
**DNA ligase**