How to Make and Run an Agarose Gel (DNA Electrophoresis)

Gel electrophoresis is a method that separates (based on size, electrical charge and other physical properties) macromolecules such as nucleic acids or proteins.
The electrophoresis term is used to describe the migration of charged particle under the influence of an electric field. Thus gel electrophoresis refers is the technique in which molecules are forced across a span of gel, motivated by an electrical current. On either end of the gel there are activated electrodes that provide the driving force. Therefore a molecule's properties especially the possession of ionisable groups, determine how rapidly an electric field can move the molecule through a gelatinous medium.
One very important application for gel electrophoresis is in DNA Technology. Biotechnology has for thousands of years been used by people who have used yeast to make flour into bread and grapes into wine. We are now using biotechnology to study the basic processes of life, diagnose illnesses, and develop new treatments for diseases. Some of the tools of biotechnology are natural components of cells. For example restriction enzymes are made by bacteria to protect themselves from viruses. They inactivate the viral DNA by cutting it in specific places. DNA ligase is an enzyme that exists in all cells and is responsible for joining together strands of DNA. Restriction enzymes can be used to cut DNA at specific sequences called recognition sites. They then rejoin the cut strands with DNA ligase to new combinations of genes. Recombinant DNA sequences contain genes from two or more organisms.
This technique has allowed researchers to gain the ability to diagnose diseases such as sickle cell anemia, cystic fibrosis, and Huntington's chorea early in the course of the disease. Many researchers are also applying the techniques of biotechnology to find new treatments for genetic diseases.
DNA technology has triggered research advances in almost all fields of biology. Currently hundreds of useful products are produced by genetic engineering. It has become routine to combine genes from different sources, usually different species--in test tubes, and then transfer this recombinant DNA into living cells where it can be replicated and expressed.
The most important achievements resulting from recombinant DNA technology have been  advances in our basic understanding of eukaryotic molecular biology. For example, only through the use of gene-splicing techniques have the details of eukaryotics gene arrangement and regulation been opened to experimental analysis.
Gel Electrophoresis is one of the staple tools in molecular biology and is of  critical value in many aspects of genetic manipulation and study. One use is the identification of particular DNA molecules by the band patterns they yield in gel electrophoresis after being cut with various restriction enzymes. Viral DNA, plasmid DNA, and particular segments of chromosomal DNA can all be identified in this way. Another use is the isolation and purification of individual fragments containing interesting genes, which can be recovered from the gel with full biological activity.
Gel electrophoresis makes it possible to determine the genetic difference and the evolutionary relationship among species of plants and animals. Using this technology it is possible to separate and identify protein molecules that differ by as little as a single amino acid.