Non-constitutive genes express themselves only when needed, are also called as

Options

A. structural gene
B. promoter gene
C. house-keeping genes
D. luxury genes

Answer

**Step-by-Step Solution:**

1. **Understanding Non-Constitutive Genes:**
- Non-constitutive genes are genes that do not express themselves continuously but are activated only when required by the cell. This means they are not always "on."

2. **Identifying the Correct Term:**
- The question asks for the term that describes non-constitutive genes. We need to evaluate the options provided:
- Structural gene
- Promoter gene
- Housekeeping gene
- Luxury genes

3. **Analyzing Each Option:**
- **Structural Gene:** These genes code for proteins or RNA that are necessary for the structure and function of the cell. They are typically constitutive, meaning they are always expressed.
- **Promoter Gene:** This term refers to a DNA sequence that initiates the transcription of a gene. It is not a type of gene that expresses itself but rather a regulatory element, so this option is incorrect.
- **Housekeeping Gene:** These genes are essential for basic cellular functions and are constitutively expressed in all cells. Therefore, they do not fit the definition of non-constitutive genes.
- **Luxury Genes:** These genes are expressed only under specific conditions or when needed, making them the correct answer.

4. **Conclusion:**
- Based on the analysis, the correct answer to the question is "luxury genes," as they are the non-constitutive genes that express themselves only when needed.

**Final Answer:**
Non-constitutive genes express themselves only when needed, and they are also called luxury genes.

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