Gel electrophoresis can separate
nucleic acids that differ in size.
DNA fragments created by restriction enzymes are separated based on
their rate of movement through a gel in an electric field.
How far a DNA molecule travels is inversely proportional to its
After the current is turned off, a dye is added; this reveals the
separated bands by fluorescing in ultraviolet light.
Restriction fragment analysis.
The normal allele of the beta-globin gene, which produces a subunit
for hemoglobin, has two sites recognized by the Dde I restriction
enzyme, yielding three restriction fragments.
The sickle-cell mutation destroys one of the Dde I restriction sites.
Digestion of mutant DNA with Dde I generates two fragments rather than
the normal three, yielding a restriction fragment length polymorphism
These fragments can be identified by gel electrophoresis.