1. KEY CONCEPT DNA fingerprints (DNA testing) identify living organisms at the molecular level.
(mother) (child 1) (child 2) (father)

2. (code for nothing or unknown…)
DNA Testing
Human Genome
About 20% genes
(code for proteins)
About 80% junk
(code for nothing or unknown…)
Highly repetitive nucleotides
Random nucleotides

3. More on DNA testing….
DNA testing uses the repetitive nucleotides because these vary among people.

4. Collect cells Extract DNA
Procedure
Collect cells
Extract DNA
Sometimes there is very little DNA available. If so, it can be copied or replicated in a process called Polymerase Chain Reaction (PCR).
Enzymes and a thermocycler (heating/cooling machine) mimic our body’s process of DNA replication.

5. Example: EcoR1 might cut DNA at every CAT
Procedure continued . . .
3. Add restriction digest (enzyme) which cuts the DNA into fragments at specific places.
Example: EcoR1 might cut DNA at every CAT
Each person’s DNA will be cut into different sized pieces—some short, some long.

6. Agarose Gel 4. Load into gel electrophoresis unit:
Procedure continued….
4. Load into gel electrophoresis unit:
Positive Negative
End End
Agarose Gel
Wells into which DNA is loaded

7. Larger DNA fragments move slowly Smaller DNA fragments move quickly
Procedure continued….
Electrical current causes negatively charged DNA pieces to “run” to the positive end.
Larger DNA fragments move slowly
Smaller DNA fragments move quickly
6. When the current is turned off, DNA fragments will stop in different places, creating a “fingerprint.”

8. Example:

9. Determine family relationships
Uses of DNA Testing
Criminal cases
DNA found at crime scenes is matched to suspects
Blood, skin, saliva, hair roots, sperm, bone marrow, etc.
Match plant material at crime scenes to material on suspect
Determine paternity
Determine family relationships
Reunite children with their parents
Confirm family relationships for immigration

10. More uses of DNA testing….
Determine relationship of fossils
Studying biodiversity
Relationships between new animal or plant species
Track true “native” species

11. More uses of DNA testing…
Identify the remains of soldiers
Identify viral or bacterial agents quickly
Track genetically modified crops