What are plasmids, often used in genetic engineering

Options

A. Extrachromosomal DNA
B. Nuclear DNA
C. Membrane bound organelle
D. DNA attached to mitochondria

Answer

### Step-by-Step Solution:

1. **Definition of Plasmids**:
- Plasmids are small, circular pieces of DNA that exist independently of chromosomal DNA within a cell. They are classified as extra chromosomal DNA.

2. **Characteristics of Plasmids**:
- Plasmids are distinct from chromosomal DNA because they are not part of the cell's main genetic material. They are separate entities that can replicate independently of the chromosomal DNA.

3. **Functionality**:
- Due to their ability to replicate independently, plasmids can carry and express genes that may provide beneficial traits to the host organism, such as antibiotic resistance or the ability to metabolize unusual substances.

4. **Role in Genetic Engineering**:
- Plasmids are widely used in genetic engineering because they can be easily manipulated. Scientists can insert foreign DNA into plasmids, allowing for the introduction of new genes into organisms. This is often done to produce proteins, study gene function, or create genetically modified organisms (GMOs).

5. **Conclusion**:
- In summary, plasmids are extra chromosomal DNA that replicate independently and are extensively utilized in genetic engineering due to their ability to carry and express foreign genes.