The name secondary messenger is given to

Options

A. cAMP
B. ATP
C. ADP
D. DNA

Answer

### Step-by-Step Solution:

1. **Understanding Secondary Messengers**:
- Secondary messengers are intracellular signaling molecules that are produced in response to the binding of an extracellular signaling molecule (like a hormone or neurotransmitter) to a receptor on the cell surface.

2. **Role of Secondary Messengers**:
- These messengers are crucial for transmitting signals from the cell membrane to various intracellular targets, leading to a cascade of biochemical reactions within the cell.

3. **Characteristics of Secondary Messengers**:
- They are typically small molecules that can diffuse rapidly within the cell. They are often produced in response to the activation of a receptor by a signaling molecule that cannot cross the plasma membrane due to its polarity.

4. **Examples of Secondary Messengers**:
- Common examples include cyclic AMP (cAMP), cyclic guanosine monophosphate (cGMP), and calcium ions (Ca²⁺).

5. **Analyzing the Options**:
- **cAMP (Cyclic AMP)**: This is a well-known secondary messenger involved in many signaling pathways.
- **ATP (Adenosine Triphosphate)**: This is primarily an energy currency of the cell and not a secondary messenger.
- **ADP (Adenosine Diphosphate)**: This is also a nucleotide and not classified as a secondary messenger.
- **DNA**: This is a nucleic acid and does not function as a secondary messenger.

6. **Conclusion**:
- Based on the definitions and examples discussed, the correct answer to the question is **cAMP (Cyclic AMP)**, as it is the only option that qualifies as a secondary messenger.

### Final Answer:
The name secondary messenger is given to **cAMP (Cyclic AMP)**.

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