Agarose gel electrophoresis is the most effective way of separating DNA fragments of varying sizes ranging from bp to 25 kb 1. Agarose is isolated from the seaweed genera Gelidium and Gracilaria, and consists of repeated agarobiose L- and D-galactose subunits 2.
During gelation, agarose polymers associate non-covalently and form a network of bundles whose pore sizes determine a gel's molecular sieving properties. Combined with PCR, agarose gel electrophoresis can be a powerful technique for identifying individuals based on their genetic code. The human genome contains many regions of short repeats, the number of which vary uniquely between individuals.
By targeting these regions with specific PCR primers, a profile of band on an electrophoresis gel corresponding to these regions can be created that is unique to that individual. This technique, known as DNA fingerprinting, can be used in areas such as forensics for criminal investigations, genealogy and parentage testing. Electrophoresis can be used in a range of diagnostic tests, primarily in the screening of genetic disorders but also to identify abnormal proteins.
DNA can be extracted from patients, or even from embryos for pre-implantation screening, and subject to PCR and agarose gel electrophoresis to confirm the presence of certain genes or genetic abnormalities. Agarose gel electrophoresis can also be applied to some proteins, for example to study blood chemistry to determine suitability of certain medical treatments. The wide range of applications, both academic and clinical make agarose gel electrophoresis an extremely important technique.
Although the recent advent of next generation sequencing technologies has the potential to replace many of the current uses of agarose gels, their ease of use and versatility mean that this technique is likely to persist for the foreseeable future. The popularity of agarose gel electrophoresis is partly due to its simplicity. The equipment required is easy to use and takes little training to operate correctly. The main components are discussed below.
The gel tank, also called a gel box, is the main component of the horizontal agarose gel electrophoresis system. Generally, a gel tank will consist of a plastic container with a raised centre platform where the gel is places on a secondary support called a gel tray. At either end of the tank, electrodes made from an inert conductive material, most commonly platinum, are fixed and wired to connectors to allow the connection to the power supply.
Finally, a lid sits on the gel tank to prevent access to the chamber while high voltage is applied to the buffer. Cleaver Scientific manufactures gel tanks in a range of sizes for different applications and can custom manufacture systems for niche applications.
Take a look at the selection chart and browse our product pages for more information. Now available with 20 x 25cm, 20 x 20cm, 20 x 15cm or 20 x 10cm gel trays Run up to samples. To apply an electrical field to the gel, you will need an electrophoresis power supply. These power supplies are specifically manufactured for electrophoresis applications and features very stable voltage and current outputs to prevent fluctuations in migrations speed.
A good power supply with allow you to set either constant current or voltage depending on the requirement of the experiment, and more advanced supplies will allow programming of individual steps at different parameter values. At Cleaver scientific we have a range of electrophoresis power supplies for all applications. Each power supply has a 2. Constant voltage, current and power options are available as well as pre-programmed or customer programmed conditions allowing users to save and repeat their experiments for exceptional reproducibility.
For the final stage of the technique, gel imaging, you will need a gel documentation system as described above. Cleaver Scientific have a whole range of gel documentations to suite any budget or requirement. Take a look at our selection guide to find the best option for you and browse our product pages for more information.
Proteins, however, are not negatively charged; thus, when researchers want to separate proteins using gel electrophoresis, they must first mix the proteins with a detergent called sodium dodecyl sulfate. This treatment makes the proteins unfold into a linear shape and coats them with a negative charge, which allows them to migrate toward the positive end of the gel and be separated. Finally, after the DNA, RNA, or protein molecules have been separated using gel electrophoresis, bands representing molecules of different sizes can be detected.
Related Concepts This is how agarose electrophoresis separates different DNA molecules according to their size. The gel is stained with ethidium bromide so you can visualize how these DNA molecules resolved into bands along the gel.
Southern blotting may also be used as a visualization technique for agarose gels. Unknown DNA samples are typically run on the same gel with a "ladder. So after you run out your sample, you can compare the unknown fragments to the ladder fragments and determine the approximate size of the unknown DNA bands by how they match up to the known bands of the ladder.
Additional images from Wikimedia via Jacopo Werther electrophoresis machine and Mnolf gel electrophoresis. Guruatma "Ji" Khalsa. Agarose Gel Electrophoresis. Scientists, teachers, writers, illustrators, and translators are all important to the program. If you are interested in helping with the website we have a Volunteers page to get the process started.
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