Unwinding of double helix DNA is brought about by _____ , which is ______ dependent

Options

A. Topoisomerase,ATP
B. Helicase, ADP
C. Helicase, ATP
D. Topoisomerase, GTP

Answer

To solve the question "Unwinding of double helix DNA is brought about by _____ , which is ______ dependent," we need to identify the enzyme responsible for unwinding DNA and the energy source it requires.

### Step-by-Step Solution:

1. **Understanding DNA Structure**:
- DNA is structured as a double helix, where two strands are held together by hydrogen bonds between complementary bases.

**Hint**: Recall that the double helix structure is stabilized by hydrogen bonds.

2. **Identifying the Process of Unwinding**:
- Unwinding refers to the separation of the two strands of DNA, which involves breaking the hydrogen bonds between them.

**Hint**: Think about what happens during DNA replication or transcription when the strands need to separate.

3. **Recognizing the Enzyme Involved**:
- The enzyme responsible for unwinding the DNA double helix is called helicase. The term "helicase" indicates its function: "heli" refers to helix, and "case" means to break down.

**Hint**: Remember that helicase is essential for processes like DNA replication.

4. **Determining the Energy Source**:
- The unwinding process requires energy, which is provided in the form of ATP (adenosine triphosphate). ATP is the primary energy currency in cells.

**Hint**: Consider what energy molecules are commonly used in cellular processes.

5. **Final Answer**:
- Therefore, the complete answer to the question is: "Unwinding of double helix DNA is brought about by **helicase**, which is **ATP** dependent."

### Summary:
- The unwinding of DNA is facilitated by the enzyme helicase, and this process requires ATP as the energy source.