1. Forensic Investigation
Bone/DNA Detectives

2. What else can we do? We now have a description
of the individual that the
bones belong to, but there
are 2 missing persons that
fit this description
Blood typing, dental records,
or DNA Fingerprinting
could all help narrow this
down.

3. What is DNA?
Deoxyribonucleic acid- biomolecule made of nucleotide subunits
DNA is found in bodily fluids,
living tissues, hair, and BONE
Humans only have 0.1% of
their DNA that is different, but
that is 3 million base pairs

4. PCR
Once we get the small amounts of DNA from the bone and missing persons, it needs to be amplified
Polymerase Chain Reaction is a process that uses a thermocycler machine and
the polymerase enzyme to
make many copies of DNA
in a short amount of time

5. Restriction Enzymes
Enzymes are proteins that speed up chemical reactions
Restriction enzymes catalyze the reaction of breaking DNA into smaller fragments
These fragments (RFLP’s) are different sizes for different individuals because of the 3 million BP that are different

6. Restriction Enzymes: Molecular Scissors
Restriction enzymes (endonuleases) cut DNA at specific sequences
What kinds of bonds are broken when restriction enzymes cut?
Covalent bonds (within a single strand)
Hydrogen bonds (between strands) as a result of the strands coming apart
Hydrogen bond
Covalent bond

7. Origins of Restriction Enzymes
Naturally found in different types of bacteria (prokaryotes)
Bacteria use restriction enzymes to protect themselves from foreign DNA
Bacteria have mechanisms to protect themselves from the actions of their own restriction enzymes
Have been isolated and sold for use in lab work

8. Examples of Restriction Enzymes
Organism source
Recognized Sequence
EcoRI
Escherichia coli
5' GAATTC 3’ 3' CTTAAG 5’
TaqI
Thermus aquaticus
5' TCGA 3’ 3' AGCT 5’
HindIII
Haemophilus influenzae
5'AAGCTT 3’ 3'TTCGAA 5’
BamHI
Bacillus amyloliquefaciens
5' GGATCC 3’ 3' CCTAGG 5’
AluI
Arthrobacter luteus
5' AGCT 3’ 3' TCGA 5’
Bases in blue are the actual bases that restriction enzymes cut between. In many cases, there are multiple subunits of a restriction enzyme– each subunit recognizes a particular sequence on one of the strands then cuts it at a certain distance away from that. Recognized sequences for restriction enzymes tend to be palindromic (read the same backwards and forwards)

9. Electrophoresis DNA is too small to see with the naked eye
DNA is loaded into an agarose (sugar) gel
We use electrophoresis (movement due to an electrical current) to separate the different size DNA fragments
DNA has a negative charge (phosphate groups) and is repelled by the negative side of the apparatus and attracted to the positive side (like repels, opposites attract)

10. Smaller pieces of DNA move faster (further) because they have less frictional resistance in the agarose.

11. Uses Can be used for crime scene to match suspect and crime scene DNA
Can be used in paternity cases to match baby with possible fathers
Can be used in forensic analysis to match bone DNA with missing person DNA