DNA Fingerprinting

1
DNA Fingerprinting
DNA fingerprinting is not taking someones
fingerprint. It is cutting up a DNA strand and
separating them by size.
2
Restriction Enzymes

• Because everyones DNA is so similar (there is
  only a 0.1 difference among people), the easiest
  way to differentiate between peoples DNA is to
  use Restriction Enzymes
• A Restriction Enzyme cuts a persons DNA like
  scissors, making cuts wherever it recognizes a
  specific sequence of base pairs
• The DNA will be cut into fragments with different
  lengths, forming a strand like this

3
Agarose Gel Electrophoresis

• How can we see these different lengths?
• The answer is a process galled agarose gel
  electrophoresis.
• Little things move faster than big things, so the
  small fragments of DNA will travel farther than
  the large fragments
• We put the DNA into the gel box, and we run
  electricity through them
• DNA is negatively charged, so it is attracted to
  the positive force at the other end of the gel
  box.
• The DNA fragments are separated by size, with the
  smaller fragments traveling farther than the
  larger ones

4
Staining DNA

• Because DNA is colorless, it is not immediately
  visible in the gel.
• Therefore, we will add dye to help see the DNA,
  and later stain the gels to make it even easier
  to see
• After the staining, we should be able to see all
  the DNA fragments, and be able to match the DNA
  at the crime scene to the right suspect

5
NOW... Let's begin!