The enzyme which helps to cut one strand of DNA duplex to release tension of coiling of two strands is

Options

A. DNA ligase
B. DNA polymerase 1
C. Topoisomerase
D. Helicases or unwindases

Answer

To answer the question regarding which enzyme helps to cut one strand of the DNA duplex to release tension from the coiling of the two strands, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding DNA Structure**:
- DNA is a double helix made up of two strands that run in opposite directions (antiparallel). Each strand has a 5' end and a 3' end.

2. **Recognizing the Need for Tension Release**:
- During DNA replication, the strands need to be unwound to allow for the synthesis of new strands. This unwinding creates tension in the DNA molecule.

3. **Identifying Relevant Enzymes**:
- Several enzymes are involved in DNA replication:
- **Helicase**: Unwinds the DNA strands.
- **DNA Polymerase**: Synthesizes new DNA strands.
- **DNA Ligase**: Joins Okazaki fragments on the lagging strand.
- **Topoisomerase**: Relieves the tension created by the unwinding of the DNA.

4. **Focusing on Topoisomerase**:
- Topoisomerases are specifically responsible for cutting the DNA strands to relieve the tension. There are two types:
- **Topoisomerase I**: Cuts one strand of the DNA.
- **Topoisomerase II**: Cuts both strands of the DNA.

5. **Concluding the Answer**:
- The enzyme that specifically helps to cut one strand of the DNA duplex to release the tension of coiling is **Topoisomerase I**.

### Final Answer:
The enzyme which helps to cut one strand of DNA duplex to release tension of coiling of two strands is **Topoisomerase I**.

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