How are DNA fragments separated in gel electrophoresis?

DNA electrophoresis is a standard laboratory technique used to identify, quantify, and purify DNA fragments. DNA electrophoresis involves loading DNA samples into the wells of an agarose or acrylamide gel and subjecting it to an electric field.

DNA fragments have a net negative charge; when subjected to an electric field, the negatively charged nucleic acid fragments migrate towards the positive electrode. The length of DNA fragments is a primary factor that influences the rate of migration—shorter DNA fragments travel faster through the gel matrix than longer fragments. Therefore, DNA electrophoresis results in separation—or resolution—of DNA fragments based on size.

Thermo Fisher Scientific provides high-quality gels, reagents, and devices to support the DNA electrophoresis workflow.

A triptych of the three-step workflow using precast gels

Thermo Fisher Scientific’s precast gel technology allows rapid separation of DNA fragments and offers unparalleled convenience when compared to traditional DNA electrophoresis. Precast gels are available as Invitrogen E-Gel agarose gels, and Invitrogen Novex TBE polyacrylamide gels.

Supplies for pour-your-own agarose gel electrophoresis including UltraPure agarose powder, running buffer, SYBR Safe, and ladders in original packages

To craft a gel of choice, use UltraPure agarose powder or UltraPure acrylamide powder; these high quality gels allow for superior resolution and the formation of sharp bands. Agarose gels can also be cast with TopVision agarose tablets.

Loading samples into gel wells for DNA electrophoresis

To load and to monitor the migration of DNA samples, Thermo Fisher Scientific offers gel loading buffers including Invitrogen BlueJuice Gel and TrackIt loading buffers .

Power Snap Plus: gel running and gel imaging device
Invitrogen E-Gel Power Snap Electrophoresis System

The all-in-one Invitrogen E-Gel Power Snap Electrophoresis System is designed for fast and convenient E-Gel agarose gel electrophoresis, from DNA sample loading to gel image. With dry precast E-Gel agarose gel technology, you can run DNA samples in as little as 10 minutes and observe sample separation in real time. It is the only benchtop system that seamlessly integrates DNA sample separation and gel imaging into one workflow.

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Nucleic acid electrophoresis products
Explore Thermo Fisher Scientific’s suite of products for all your electrophoresis needs.

Nucleic acid electrophoresis education
Learn about gel electrophoresis basics, workflow, considerations, applications, and troubleshooting for separation and analysis of nucleic acids.

DNA and RNA protocols
Find easy-to-follow protocols for everyday experiments, including agarose protocols and mRNA protocols.


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Find tips, troubleshooting help, and resources for your nucleic acid purification and analysis applications.

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