Matthew Robbins, The Ohio State University
Gel electrophoresis is commonly used in plant breeding and genomics for genotyping with molecular markers, but there are several other applications as well (see below). For example, specific DNA fragments used as markers and isolated from individual plants are amplified by the polymerase chain reaction (PCR) and the resulting DNA fragments are subsequently loaded on a gel. The gel is a solid, gelatin-like substance used to separate DNA fragments based on size. The gel is placed in a conductive salt buffer to which an electrical field is applied. As the negatively-charged DNA fragments migrate toward the positive pole, the gel acts as a size filter, with smaller fragments migrating faster than larger fragments.
In addition, this video illustrates the basics of DNA extraction and gel electrophoresis in tomato:
Another animation on gel electrophoresis can be found at the Dolan DNA Learning Center, part of The Cold Spring Harbor Laboratory:
The Genetics Science Learning Center at the University of Utah also has an animation on gel electrophoresis:
DNA can be separated by electrophoresis to:
Development of this lesson was supported in part by the National Institute of Food and Agriculture (NIFA) Solanaceae Coordinated Agricultural Project, agreement 2009-85606-05673, administered by Michigan State University. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the United States Department of Agriculture.