In human beings, sex determination has recently been studied in great detail using techniques of molecular biology. The most important gene located on Y chromosome and involved in sex determination is:-

Options

A. SRY gene
B. SXI gene
C. ZFY gene
D. Tra gene

Answer

**Step-by-Step Solution:**

1. **Understanding the Question:**
The question asks for the most important gene located on the Y chromosome that is involved in sex determination in human beings.

2. **Identifying the Options:**
The options provided are:
- A) SRY gene
- B) SXI gene
- C) ZFY gene
- D) TRAZ gene

3. **Analyzing Each Option:**
- **Option A: SRY gene** - This gene is known as the Sex-determining Region Y gene. It plays a crucial role in male sex determination by initiating the development of testes.
- **Option B: SXI gene** - This gene is involved in sexual development in Drosophila (fruit flies), not in humans, making it irrelevant to the question.
- **Option C: ZFY gene** - This gene encodes a zinc finger protein found on the Y chromosome, but it is not the primary gene responsible for sex determination.
- **Option D: TRAZ gene** - This gene is related to the transfer of genetic material in bacteria and does not play a role in sex determination in humans.

4. **Conclusion:**
Based on the analysis, the SRY gene (Option A) is the most important gene located on the Y chromosome involved in sex determination in humans.

5. **Final Answer:**
The correct answer is **A) SRY gene**.

---