9 3 DNA Fingerprinting KEY CONCEPT DNA fingerprints

9. 3 DNA Fingerprinting KEY CONCEPT DNA fingerprints (DNA testing) identify living organisms at the molecular level. (mother) (child 1) (child 2) (father)

9. 3 DNA Fingerprinting DNA Testing Human Genome About 20% genes (code for proteins) About 80% junk (code for nothing or unknown…) Highly repetitive nucleotides Random nucleotides

9. 3 DNA Fingerprinting More on DNA testing…. DNA testing uses the repetitive nucleotides because these vary among people.

9. 3 DNA Fingerprinting Procedure 1. Collect cells 2. 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.

9. 3 DNA Fingerprinting Procedure continued. . . 3. Add restriction digest (enzyme) which cuts the DNA into fragments at specific places. Example: Eco. R 1 might cut DNA at every CAT Each person’s DNA will be cut into different sized pieces—some short, some long.

9. 3 DNA Fingerprinting Procedure continued…. 4. Load into gel electrophoresis unit: Positive End Negative End Agarose Gel Wells into which DNA is loaded

9. 3 DNA Fingerprinting Procedure continued…. 5. 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. ”

9. 3 DNA Fingerprinting Example:

9. 3 DNA Fingerprinting Uses of DNA Testing ØCriminal cases Ø DNA found at crime scenes is matched to suspects Ø Blood, skin, saliva, hair roots, sperm, bone marrow, etc. Ø Match plant material at crime scenes to material on suspect ØDetermine paternity ØDetermine family relationships Ø Reunite children with their parents Ø Confirm family relationships for immigration

9. 3 DNA Fingerprinting More uses of DNA testing…. Ø Determine relationship of fossils Ø Studying biodiversity ØRelationships between new animal or plant species ØTrack true “native” species

9. 3 DNA Fingerprinting More uses of DNA testing… ØIdentify the remains of soldiers ØIdentify viral or bacterial agents quickly ØTrack genetically modified crops