The mobile genetic element is

Options

A. transposon
B. mutation
C. endonuclease
D. variation

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for the definition or identification of a mobile genetic element.

2. **Identifying Options**: The options provided are transposon, mutation, endonuclease, and variation. We need to analyze each option to find out which one is a mobile genetic element.

3. **Definition of Transposon**: A transposon, also known as a "jumping gene," is a DNA sequence that can change its position within the genome. This movement can create mutations and alter the cell's genetic identity and genome size.

4. **Characteristics of Transposons**:
- They can move around within the genome.
- They can increase their number of copies.
- They can change their location within the genome.
- They can affect the activity of nearby genes, either enhancing or inhibiting their function.

5. **Analyzing Other Options**:
- **Mutation**: Refers to sudden inheritable changes in the genetic material, but does not imply mobility.
- **Endonuclease**: This is an enzyme that cuts DNA at specific sites, not a genetic element.
- **Variation**: Refers to changes in the genetic makeup but does not specifically denote mobility.

6. **Conclusion**: Based on the definitions and characteristics analyzed, the correct answer to the question "The mobile genetic element is" is **Transposon**.

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