Biology Fun-damentals

Aug 10, 2016

Gene Cloning: vectors, plasmids, ligations, and transformation - oh my!

What is the goal or what is gene cloning?
The goal is to get a single copy of the gene from an animal and into an archive. The rest is just the individual steps necessary to do this.

Step Description Biology Jargon
1     Get a copy of the gene from the animal PCR
2     Put the gene in an archival format Ligation into a plasmid
3     Make backup copies or archive it Bacterial transformation
4     Confirm that the copies match the original    Sequence the insert
5     Retrieve a copy to use Miniprep

What is a vector?
A vector is a small, self contained piece of DNA that can be added to an organism, typically bacteria.

Usually, the vector contains genes within it that give the bacteria new traits, such as antibiotic resistance. You can then select bacteria with these traits to check that the vector is present. Note that the vector may contain multiple genes, some of which may be entirely foreign to the orgaism. For instance it is possible to ‘archive’ a mouse gene in E. coli.

Bacteria are usually our ‘container’ of choice for several reasons. They grow quickly allowing you to get many copies of your archived gene. Perhaps more importantly, it is very easy to insert the vector. Bacteria naturally take up peices of DNA called plasmids and incorporate them into their genetic material.

An example of selecting for bacteria that have a vector. In this case, the trait that the vector added also includes blue coloration. A petri dish with growth media and small dots that are bacterial colonies growing on it. Some of the dots are white while others are blue. © wikimedia. The work of Stefan Walkowski.

Ok. So what is a plasmid?
Well, in many cases, the vector is a plasmid. In this case, the plasmid is a round piece of DNA that is separate from the main genetic material. Importantly a plasmid loose in the environment can be added to an existing bacteria aka incorporated. Additionally, it copied independently of the main genetic material and at the control of the scientist, which is necessary for some applications.

Other explanations or learning material: