MH
SBI 4U
(DNA)
Deoxyribonucleic
acid
• DNA is thought of as a “recipe for life”
• DNA is the nucleic acid that contains the genetic instructions
that bring us to life
• Found in the nucleus of every cell in the human body
• Four bases: A, T, C, G
• Our DNA is 99.9% identical
• 0.1 % is different, 3 million base pairs
Dr. Alec Jeffreys
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Dr. Jeffreys discovered the use of DNA in forensics
Fingerprinting was the first method of evidence
Searched for a more accurate method
DNA in forensic criminology is the use of DNA to
match a criminal to a crime scene
• Which was powerful enough to implicate or
eliminate a suspect
Southern Hybridization Method
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Extracted DNA from evidence is compared
to DNA extracted from reference samples
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Electrophoresis
Negatively charged DNAs migrate towards
the positive electrode
Smaller DNA fragments move faster
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Transferred to a nylon membrane (like
paper)
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A single locus probe is a DNA or RNA
sequence that is able to hybridize with
DNA from a specific restriction
fragmentation
Single locus probes are usually tagged
with a radioactive label for easy detection
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We can extract DNA from almost everything
Blood
Hair
Semen
Saliva
Skin
• We call this evidence “trace evidence”
• “May” be enough evidence to put someone
away (Ex. taxi)
Murder at Rodman Dam, 1988
• In July 1987, Randall Scott Jones and
Chris Reesh were target shooting (with
.3-30 rifles)
• Truck got stuck in a sandpit
• Found a couple sleeping in their truck,
Matthew Brock and Kelly Lynn Perry
• They ended up driving away with both
trucks
• What happened?
• Bodies were found in a
nearby forest (both shot)
• Kelly appeared to have been
sexually abused
• Warrant was issued by court
• Confessed as
soon as the DNA
results were
announced
DNA Databases
• First Type: Known DNA
• Second Type: Unknown DNA
Combined
DNA Index
System
(CODIS)
Wrongfully Accused
• Worked on freeing the
wrongfully accused
• Many were set free
• Saved from the death
penalty
• Various speeches all over
the internet
Suspect #2
Pig Experiment
• Used to train forensic
scientists who get
involved right away
• Pigs have similar skin to
a human
• Used to build their
knowledge on the
insects that decompose
a body
Conclusion
• Using DNA in forensic
criminology has
helped the justice
system greatly
• Has sent/taken
people to/from
prison
• DNA lasts forever
• We can improve on
the time it takes to
analyze DNA
References
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_____. (1999). Forensic DNA. Retrieved from: http://library.thinkquest.org/28599/courtroom.htm
Human Genome Project Information. (2009). DNA Forensics. Retrieved from:
http://www.ornl.gov/sci/techresources/Human_Genome/elsi/forensics.shtml
Nute, Dale. (1999). Advice about a Career in Forensic Science. Retrieved from:
htpps://www.criminology.fsu.edu/faculty/nute/FScareers.html
William C. Thompson. (2008). The Potential for Error in Forensic DNA Testing (and How That
Complicates the Use of DNA Databases for Criminal Identification). Retrieved from:
http://www.councilforresponsiblegenetics.org/pageDocuments/H4T5EOYUZI.pdf
_____. (2010). Forensic DNA analysis in the identification of human
remains in mass graves. Retrieved from: http://academicjournals.org/JCPFM/PDF/Pdf2010/Mar/Jakovski et al.pdf
Advancing Criminal Justice Through DNA Technology. (2010). History of Forensic DNA Analysis. Retrieved from:
http://www.dna.gov/basics/analysishistory
_____. (2008). Has DNA testing led to significant improvements in the criminal justice system?. Retrieved from:
http://deathpenalty.procon.org/view.answers.php?questionID=001189
CBC News Canada. (2010). Key events in the Bernardo/Homolka Case. Retrieved from:
http://www.cbc.ca/news/canada/story/2010/06/16/f-bernardo-homolka-timeline.html
National Criminal Justice Reference Service. (2003). Forensic Science. Retrieved from:
http://www.policyalmanac.org/crime/archive/forensic_science.shtml
Cold Spring Harbor Laboratory. (2003). State of Florida vs. Jones and Reesh, Murder at Rodman Dam, 1988. Retrieved from:
http://www.dnai.org/d/index.html?m=1,3
Federal Bureau of Investigation. (2007). Combined DNA Index System (CODIS). Retrieved from: http://www.fbi.gov/about-us/lab/codis
_____. (2001). What is DNA?. Retrieved from: http://www.ojp.usdoj.gov/ovc/publications/bulletins/dna_4_2001/dna2_4_01.html
The Biology Project. (1996). DNA Forensics Problem Set 1. Retrieved from:
http://www.biology.arizona.edu/human_bio/problem_sets/DNA_forensics_1/01t.html
Detective Ray Rikic ( Head of the Hamilton Forensics Police Department)
Sites for Pictures
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http://www.molecularstation.com/images/southern-blot.jpg
http://farm1.static.flickr.com/69/205471921_05b52359f6.jpg
http://evolution.berkeley.edu/evolibrary/images/news/dnafingerprints.gif
http://3.bp.blogspot.com/_6WSTYpSuKf0/SwxRK03FeWI/AAAAAAAAABw/ON7EJC
816Cs/s1600/SCANNER.jpg
http://3.bp.blogspot.com/_DAgs4uhkNSE/SSH4bh9l6_I/AAAAAAAAABs/M_hpUBCt
NRw/s400/DNA+01.jpg
http://bernews.com/wp-content/uploads/2010/08/dna_crime.jpg
http://www.newsnet14.com/images/Codis.jpg
http://www2.fbi.gov/hq/lab/lab2006/images/investigations2.jpg
http://merahjinggabiru.files.wordpress.com/2012/01/question-mark.jpg
http://www.uwindsor.ca/dailynews/2011-10-13/pig-experiment-chance-to-shareforensic-knowledge-with-windsor-police-officers
http://www.gamepimpin.com/content/icons/csi-icon-1.jpg
http://www.georgetandy.com/evidence_low_resolution-blk-alpha.jpg