Plasmid

In case you weren't aware I have begun conducting research on Y. pestis (bubonic plague) and its close relative Y. pseudotuberculosis. To fill you in on what I am doing for research I feel it necessary to teach you some basic things about molecular biology. To anyone who is interested, the first thing you need to understand are plasmids.

Bacteria as you might already know are prokaryotes. This means they have no nucleus and have very a simple structure. They are made up of an outer membrane, ribosomes, and a large circular genome of double stranded DNA. It was discovered that they sometimes have additional genetic material known as plasmids. These plasmids are circular double stranded DNA. They are often diagrammed as a circle in a circle, although they don't really look like that.

These plasmids undergo replication within bacteria and the new copy is passed on to the next generation of bacteria. These plasmids can also get integrated in the bacterial genome (see fig.). In either case the genetic material in the plasmid can have some interesting affects on the bacteria. For example, some plasmids are responsible for antibiotic resistance. Some plasmids give bacteria their pathogenic ability. Others serve no known function.

Now these plasmids can also be passed from one bacterium to another through the process of conjugation. Conjugation occurs when two bacterium come into contact, and the one with the plasmid uses a tube like structure to connect to the other bacterium. A copy of the plasmid is then passed through the tube to the other bacterium, so now both bacteria have a copy of the plasmid (see fig below).

The research I'm participating in relies on the use of plasmids and conjugation of plasmids from one species (E. coli) of bacteria to another (Y. pestis or Y. pseudotuberculosis). The research also has to do with the integration of the plasmid into the bacterium's genome.

More to come...Feel free to ask questions.