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Microbiology · Chapter 7

Anatomy of an R-Plasmid

A plasmid is a small circle of DNA that copies itself apart from the chromosome. When it carries resistance genes, we call it an R-plasmid — and a single ring can hold the machinery to copy itself, spread to new cells, and defeat several antibiotics at once. Tap each gene to see what it does.

The R-plasmid

Tap a coloured gene on the ring — or in the list — to inspect it.
The R-plasmidtap a gene to inspect it
This one plasmid defeats:
β-lactams aminoglycosides tetracyclines sulfa / trimethoprim
One ring, many jobsAn R-plasmid is not just a bag of resistance genes. It also carries an origin of replication so it can copy itself, and transfer genes so it can move to a new cell. The resistance genes ride along as cargo — often stacked together, which is why one plasmid can make a microbe resistant to many drugs at once.
R-plasmids are the main reason antibiotic resistance spreads so fast: they replicate, they hop between cells by conjugation, and they keep collecting new resistance genes.