Plasmid

Definition

A plasmid is a small, circular piece of DNA that exists independently of the chromosomal DNA in prokaryotic cells. Plasmids often carry genes that confer advantageous traits such as antibiotic resistance.

5 Must Know Facts For Your Next Test

1. Plasmids are commonly found in bacteria but can also be present in archaea and eukaryotic organisms.
2. They replicate independently of the host cell's chromosomal DNA.
3. Plasmids can be transferred between bacteria through processes like conjugation, transformation, and transduction.
4. Many plasmids contain genes that provide resistance to antibiotics, heavy metals, or toxins.
5. They play a significant role in genetic engineering and biotechnology as vectors to introduce new genes into organisms.

Review Questions

• What is a plasmid and how does it differ from chromosomal DNA?
• Describe how plasmids contribute to genetic diversity in prokaryotes.
• Explain the role of plasmids in antibiotic resistance.

Related terms

Conjugation:

A process by which one bacterium transfers genetic material to another through direct contact.

Transformation:

The uptake of foreign DNA from the surrounding environment by a bacterial cell.

Transduction:

The transfer of bacterial genes by viruses called bacteriophages.