Plasmids: Simplified

By Tyler Ford

We recently worked with YouTuber, Tom McFadden, to create a Plasmid Rap and introduce newcomers to the world of plasmids. As part of this process, we sent Tom a primer on plasmids and some of the ways that they can be used. We present this primer to you now with the hope that you can use it to introduce plasmids to any novice molecular biologist. You can find much more information about plasmids and their uses in our Plasmids 101 series. Happy reading!

What is a plasmid?

parts of a plasmidA plasmid is a small, circular piece of DNA naturally found in many types of bacteria. Sometimes referred to as vectors, constructs, or clones, plasmids can be replicated independently from the bacterial genome and often encode genes that give bacteria specific traits. These traits can include the ability to resist treatment with an antibiotic, the ability to kill other bacteria, and the ability to transfer the plasmid to other bacteria.

While many scientists do research on natural plasmids and their roles in biology, plasmids have also been synthetically developed as research tools with a wide variety of uses. From a research perspective, plasmids are useful because they can be easily manipulated. Scientists use molecular scissors called restriction enzymes to cut plasmids open at specific points in their DNA sequences. Scientists can then insert new components into their cut plasmids (See Figure 2). These new components often contain genes that give bacteria new traits that scientists can later study.

Scientists have even adapted plasmids so that organisms other than bacteria can maintain them in their cells and gain new traits. Importantly, because the bacteria from which plasmids are isolated grow quickly and make more of the plasmids as they grow, scientists can easily make large amounts of plasmid to manipulate and use in later work.

Simple Cloning Schematic

Applications of plasmids

Some of the many things that plasmids can be used to do include:

  • Produce large amounts of a protein so that scientists can purify and study it in a controlled setting. Read more:
  • Monitor the level of a chemical in a particular environment

biosensors encoded on a plasmid

  • Produce enzymes that will make specific, controlled changes to an organism’s genome (genome engineering)
  • Produce synthetic viruses that can be used in research or for therapeutics

plasmids encoding parts of a viral particleThere are many more things that plasmids can be used for, but we hope that you or your students have found this primer useful. You can find additional plasmid educational content on our plasmid reference pages, specific information about a variety of plasmid types on our collection pages, protocols on our protocol pages, and instructional videos on our Youtube channel. Of course, you can also request plasmids directly from Addgene and use them in your next experiment. Browse the repository to find the plasmids that best suit your experimental needs.

Subscribe to the Addgene Blog to keep up to date on our latest educational content, to learn about science careers, and to learn the latest news about plasmids coming into the repository.


Click to download Addgene's Plasmids 101 eBook

Topics: Plasmids 101, Plasmids

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