What are plasmids?

Explanation

**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, meaning they are not part of the main chromosome.

2. **Presence in Organisms**: Plasmids are primarily found in bacteria, although they can also be present in some eukaryotic organisms. They play a crucial role in the genetic makeup of these organisms.

3. **Structure of Plasmids**: Plasmids are typically circular in shape and consist of double-stranded DNA. This structure allows them to be stable and functional within the cellular environment.

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