Which of the following hormone is a derivative of tyrosine?

Options

A. Thyroxine
B. Epinephrine
C. Nor epinephrine
D. All of these

Answer

To determine which hormone is a derivative of tyrosine, we can analyze the options provided: thyroxine, epinephrine, and norepinephrine.

### Step-by-Step Solution:

1. **Understanding Tyrosine**:
- Tyrosine is an aromatic amino acid that serves as a precursor for several important hormones in the body.

2. **Analyzing Thyroxine**:
- Thyroxine (T4) is a hormone produced by the thyroid gland.
- It is synthesized from two molecules of tyrosine and four iodine atoms.
- Therefore, tyrosine is a direct precursor for thyroxine.

3. **Analyzing Epinephrine**:
- Epinephrine, also known as adrenaline, is produced in the adrenal medulla.
- The synthesis of epinephrine begins with tyrosine, which is converted to DOPA, then to dopamine, and finally to epinephrine.
- Thus, tyrosine is also a precursor for epinephrine.

4. **Analyzing Norepinephrine**:
- Norepinephrine (noradrenaline) is also produced in the adrenal medulla.
- Similar to epinephrine, norepinephrine is synthesized from tyrosine through the same pathway (tyrosine → DOPA → dopamine → norepinephrine).
- Therefore, tyrosine is a precursor for norepinephrine as well.

5. **Conclusion**:
- Since tyrosine is a precursor for all three hormones (thyroxine, epinephrine, and norepinephrine), we can conclude that all the options given are derivatives of tyrosine.

### Final Answer:
**All of the above hormones (thyroxine, epinephrine, and norepinephrine) are derivatives of tyrosine.**

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