What is the role of plasmids in prokaryotes?
Plasmids are small, circular, double-stranded DNA molecules found in prokaryotic
cells, such as bacteria. They are separate from the chromosomal DNA and replicate
independently. Plasmids are not an essential part of the prokaryotic genome, but
they can confer some useful traits to the bacterial cell, such as antibiotic resistance,
metabolic pathways, and virulence factors.
The role of plasmids in prokaryotes is varied, but it generally involves providing the
bacterial cell with some selective advantages in a changing environment. For
instance, some plasmids carry genes that confer antibiotic resistance to the bacterial
cell, which enables it to survive in the presence of antibiotics in the environment.
Plasmids that carry virulence factors can increase the pathogenicity of the bacterial
cell, making it more likely to cause disease. Plasmids can also carry genes that code
for enzymes, such as those involved in the degradation of organic compounds,
which can aid the bacterial cell in utilizing different sources of nutrients.
Plasmids can be transferred between cells via horizontal gene transfer mechanisms
such as conjugation, transformation, and transduction. This enables the bacterial
cells to share the genes encoded on the plasmids, even across different species of
bacteria. Plasmids can also be lost by the bacterial cell over time, as they are not
essential for its survival under normal conditions.
In summary, plasmids play a significant role in shaping the genetic diversity of
prokaryotic cells, providing them with selective advantages in different environments.
Studying plasmids and their functions is crucial for understanding the evolution and
adaptation of bacterial cells in response to changing conditions.
References:
1. Fernandez-Lopez, R., & de la Cruz, F. (2014). Plasmids as models to study
macromolecular interactions. Plasmid biology, 151-171. doi: 10.1007/978-94-017-8998-5_6
2. Khan, S.A. (2014). Plasmids and their replication. Microbial genetics, 24-46. doi:
10.1007/978-94-017-8998-5_3
3. Smillie, C., Garcillán-Barcia, M.P., & Francia, M.V. (2012). Ecology of plasmid-mediated
antibiotic resistance in the clinical context. Frontiers in microbiology, 3, 14. doi:
10.3389/fmicb.2012.00014