Biotechnology: Gel
Electrophoresis
Using the new to improve
the old…..
 Our knowledge of the structure and function of
DNA is fairly new information.
 Watson & Crick - 1953
 However, in a short amount of time, our DNA
knowledge has been used to:
 Improve Identification Methods of Criminals
 Determine Maternity/Paternity
 Bioengineer products
 Blood typing was first used for these purposes,
but has limited capability because it is not
specific to each person.
Gel Electrophoresis (DNA
Fingerprinting)
 Every person has a unique sequence of
DNA.
 Enzymes can be used to cut a strand of
DNA into several pieces.
 A ‘picture’ of a person’s DNA fragments
that are separated by size is called a
DNA fingerprint.
Simulating Gel Electrophoresis
Who took Jimmy's lollipop?
The short version of how
DNA fingerprints are made
DNA is (-) charged. When you turn on the gel,
the DNA samples move across to the (+)
side.
Because the gel is porous (contains small
holes), large fragments get stuck and don’t
move far whereas small fragments move
farther.
Examples: Interpreting
DNA Fingerprints
Determining Parents
http://www.scq.ubc.ca/a-brief-tour-of-dna-fingerprinting/
Example 1: Who left the blood
stain? How do you know?
http://www.biologycorner.com/resources/DNAfinger.gif
Example 2: Who are the
parents of this soldier? How do
you know?
http://www.glencoe.com/qe/images/b136/q4318/ch13_0_c.gif