Plasmids present in the bacterial cells are :

Options

A. Circular double stranded helical DNA molecules
B. Circular double stranded helical RNA molecules
C. Linear double stranded helical RNA molecules
D. Linear double stranded helical DNA molecules

Answer

**Step-by-Step Solution:**

1. **Understanding Plasmids**: Plasmids are small, circular, double-stranded DNA molecules found in bacterial cells. They exist independently of the chromosomal DNA and can replicate on their own.

2. **Characteristics of Plasmids**:
- They are extra-chromosomal genetic elements, meaning they are not part of the bacterial chromosome.
- They are typically circular in shape.
- They consist of double-stranded DNA, which is helical in structure.

3. **Function of Plasmids**: Plasmids often carry genes that provide bacteria with advantageous traits, such as antibiotic resistance. This can help bacteria survive in environments with antibiotics.

4. **Biotechnological Applications**: Due to their ability to replicate independently and their small size, plasmids are widely used in biotechnology, particularly in the creation of recombinant DNA (rDNA) for genetic engineering purposes.

5. **Conclusion**: Based on the characteristics and functions of plasmids, the correct answer to the question is that plasmids present in bacterial cells are "circular double-stranded helical DNA molecules."

**Final Answer**: Circular double-stranded helical DNA molecules.

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