Plasmids
Start with the big picture
Most plasmids are small, circular, double-stranded DNA molecules with an origin of replication distinct from the chromosome. They replicate autonomously, and their copy number is regulated. Plasmids can carry genes for conjugation, antibiotic resistance, virulence, bacteriocin production, or the use of unusual metabolic substrates. Their capacity to move between bacteria helps spread genes, including those involved in resistance and pathogenesis. Transfer abilities vary: some plasmids encode the machinery for transfer, while others depend on assistance. Plasmids can also be lost under certain conditions and are widely used as cloning vectors. These features make plasmids relevant to bacterial adaptation, clinical microbiology, and molecular biology.
What you'll learn
- Describe plasmid structure and distinguish plasmid DNA from the bacterial chromosome.
- Explain autonomous replication and factors that influence plasmid copy number.
- Identify major plasmid classes and the advantages they may confer.
- Differentiate conjugative, mobilizable, and non-mobilizable plasmids.
- Relate plasmid transfer to antimicrobial resistance, pathogenesis, and biotechnology.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
