Horizontal Gene Transfer

Bacteria are able to exchange genes quickly within a population on small circles of DNA called plasmids. This animation shows how bacteria exchange plasmids through a process called horizontal gene transfer.

Bacterial cells are very different to our cells. They are far smaller and their DNA is not contained within a nucleus. They also have two key types of DNA, plasmid and chromosomal. Most of their DNA is present in the cell as one long strand of DNA bundled up in a single chromosome. The rest of the DNA is in the form of circular pieces of DNA called plasmids which sit outside of the main chromosome. Bacteria are able to exchange genes by the transfer of these plasmids in a process called horizontal gene transfer. This is one way that bacteria can share genes that make them resistant to antibiotics and how antibiotic resistance can spread through a population of bacteria.