Download Gel Electrophoresis

Gel Electrophoresis
Electrophoresis: DNA
Separation
 Standard tool in
biochemistry labs
 Uses
 Diagnose disease
 Identify genes and gene
structures
 Human genome project
 Understand evolution of
plants and animals
 Genetic engineering of
organisms (Example:
drought resistant crops
 Forensic science
DNA!
Extracted from animal, plant, and
bacteria cells
Individual cells are split open, and the
DNA is separated from the rest of the
cellular debris
DNA is then treated with special proteins
called restriction enzymes, which cleave
the DNA into smaller fragments
How does Electrophoresis
work?
 DNA molecules are
negatively charged
 Use electricity to
separate DNA
protein molecules
based on charge and
mass
 DNA samples are
taken from animal or
plant cells
Agarose Gel
 Used as the support
material to separate
DNA molecules
 Derived from
seaweed
 Note “wells”- DNA
solution is loaded
into these holes
Loading the Gel
 DNA loaded into gel:
mixture of different
sized DNA fragments
Loading the Gel
 Loading gel with DNA mixture + dye
 Gel is suspended in buffer which conducts electrical current
Separation of DNA
 Note applied electrical
charge- DNA is
negatively charged and
will migrate to the
positive pole
 Gel matrix acts as a
“seive” for DNA
 Large DNA molecules
cannot pass through the
small holes in the gel
 Small molecules move
easily through the gel
Running the Gel
 Electric current is applied to gel
 DNA starts to migrate through the gel
Separation of DNA
 As separation
continues, the
smaller fragments
move farther down
the gel
Molecular Markers
 A DNA molecular
marker “ladder” is
run at the same time
as your sample DNA
 Markers are of
known molecular
weights
 Markers used to
estimate the sizes of
your sample DNA
Reading the Gel
 Dye in gel reacts with
UV light, DNA is
fluorescent
 Photo taken