What are Plasmids?
Most cells contain at least one chromosome but some cells also contain an additional DNA element or elements called plasmids
. Plasmids are DNA molecules, generally circular, which can replicate in bacterial, archaeal and eukaryotic cells. They take advantage of the cellular environment of the cell but can also carry a rich diversity of genes which can be beneficial for the cell. Some plasmids confer the ability to degrade organic compounds and to fix nitrogen. Other plasmids carry antibiotic resistance genes and their spread in pathogenic bacteria is of great medical significance. Plasmids are used in molecular studies of various organisms and are important in many branches of biology, medicine, ecology and evolution as well as basic research in microbiology, molecular biology and structural biology. (Reference: Plasmids: Current Research and Future Trends ISBN: 978-1-904455-35-6)
Recommended reading on plasmid biology at Plasmid biology and current topics on microbiology research at the Microbiology Blog