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8/6/2019 Betha DNA Forensik
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DNA ForensicDNA Forensic
IdentificationIdentification
Ashley KowaleskiAshley Kowaleski
I400I400
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ObjectivesObjectives
What is forensic science?What is forensic science?
How and when did forensics begin?How and when did forensics begin?
When was DNA identification discovered?When was DNA identification discovered? What is DNA identification used to determine?What is DNA identification used to determine?
What exactly are forensic scientist looking for?What exactly are forensic scientist looking for?
What is the process does DNA identificationWhat is the process does DNA identification
involve?involve? How are criminals processed?How are criminals processed?
What is the outlook for the future?What is the outlook for the future?
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Forensic ScienceForensic Science
Process of gathering and examiningProcess of gathering and examiningevidence of a crimeevidence of a crime
First practiced forensic medicine in 1958First practiced forensic medicine in 1958
ItalyItaly
Application of medical knowledge to legalApplication of medical knowledge to legalquestionsquestions
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Unique IdentifiersUnique Identifiers
FingerprintsFingerprints When a persons handWhen a persons hand
touched a surface, it left atouched a surface, it left a
barely visible markbarely visible mark Each persons fingerprintEach persons fingerprint
is a unique identifier ofis a unique identifier ofthat person, no twothat person, no twopeoples are alikepeoples are alike
DNADNA Genetic material that isGenetic material that is
found in DNA is also afound in DNA is also a
unique identifierunique identifier Not until1985 when DNANot until1985 when DNA
became part of forensicbecame part of forensicsciencescience
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DNADNA (deoxyribonucleic acid)(deoxyribonucleic acid)
Nucleic acid that carries the genetic informationNucleic acid that carries the genetic information
Double helixDouble helix
2 long chains of nucleotides twisted and joined2 long chains of nucleotides twisted and joinedby hydrogen bondsby hydrogen bonds
Can be found in white blood cellsCan be found in white blood cells
Polymorphic: vary in shape from person toPolymorphic: vary in shape from person to
personperson
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Short Tandem RepeatsShort Tandem Repeats
(STR)(STR) STR regions are nucleotides along the backbone of aSTR regions are nucleotides along the backbone of a
chromosomechromosome
13 markers used in forensic science13 markers used in forensic science
Classified into groups depending on the size of theClassified into groups depending on the size of therepeat regionsrepeat regions Mini satellitesMini satellites
Micro satellitesMicro satellites
The chance that any two peoples DNA fingerprint for aT
he chance that any two peoples DNA fingerprint for aparticular set of regions is exceptionally smallparticular set of regions is exceptionally small 1/101/10thth of a single % of DNA, about 3 million bp, differ from oneof a single % of DNA, about 3 million bp, differ from one
person to the nextperson to the next
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The ProcessThe Process
IsolationIsolation
QuantifyingQuantifying
Polymerase Chain Reaction (PCR)Polymerase Chain Reaction (PCR)
Short Tandem RepeatShort Tandem Repeat--Polymerase ChainPolymerase ChainReaction (STRReaction (STR--PCR)PCR)
InterpretationInterpretation
DatabaseDatabase
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IsolationIsolation
Scientist extract DNA from the nucleus ofScientist extract DNA from the nucleus ofcells in tissuecells in tissue
Quality of tissue DNA samples degradesQuality of tissue DNA samples degradesas body decomposesas body decomposes
11--4 hours4 hours
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QuantifyingQuantifying
Tests are run to determine the amount ofTests are run to determine the amount ofDNA recoveredDNA recovered
Targeted amount 1 nanogram (billionth ofTargeted amount 1 nanogram (billionth ofa gram)a gram)
If inadequate quantity, isolation must beIf inadequate quantity, isolation must be
repeatedrepeated 11--2 hours2 hours
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Polymerase ChainPolymerase Chain
Reaction (PCR)Reaction (PCR) One of the most popular and widely usedOne of the most popular and widely used
techniques in molecular biologytechniques in molecular biology
Reproduces millions of exact copies ofReproduces millions of exact copies ofspecific fragments of DNAspecific fragments of DNA
Enables even highly degraded samplesEnables even highly degraded samples
to be analyzedto be analyzed 3 hours3 hours
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Polymerase Chain ReactionPolymerase Chain Reaction
(PCR)(PCR)
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Polymerase ChainPolymerase Chain
Reaction (PCR)Reaction (PCR) Based on polymerase enzymeBased on polymerase enzyme
Break apart double helix, two single strandsBreak apart double helix, two single strands
Rebuild two strands into two complete helixesRebuild two strands into two complete helixes DNA deposited into polymerases andDNA deposited into polymerases and
nucleotidesnucleotides
Repeated rapidly, doubling amount of DNARepeated rapidly, doubling amount of DNA
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STRSTR--PCRPCR
Mainly same processMainly same process
Focus solely on STR regionsFocus solely on STR regions
Since these repeat regions are usuallySince these repeat regions are usuallybounded by specific restriction enzymebounded by specific restriction enzymesites, it is possible to cut out the segmentsites, it is possible to cut out the segment
of the chromosomeof the chromosome
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Capillary ElectrophoresisCapillary Electrophoresis
(CE)(CE) Early 1990sEarly 1990s Automated analytical techniqueAutomated analytical technique Generally used for separating ions, which move atGenerally used for separating ions, which move at
different speeds when the voltage is applied dependingdifferent speeds when the voltage is applied dependingon their size and charge. The solutes are seen ason their size and charge. The solutes are seen aspeaks as they pass through the detectorpeaks as they pass through the detector
Area of each peak is proportional to their concentrationArea of each peak is proportional to their concentration Produces a chart mapping a persons exact geneticProduces a chart mapping a persons exact genetic
makeupmakeup This is the information used to compare suspects to aThis is the information used to compare suspects to a
crimecrime http://chemi.muni.cz/~analytika/ce/cehttp://chemi.muni.cz/~analytika/ce/ce--animation.gifanimation.gif
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Capillary ElectrophoresisCapillary Electrophoresis
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InterpretationInterpretation
A DNA scientist reviews the DNA profileA DNA scientist reviews the DNA profileproduced through the capillary electrophoresisproduced through the capillary electrophoresis
to determine if there is a matchto determine if there is a match STR markers are examined (2STR markers are examined (2--5 bp)5 bp)
11--3 are not enough to determine is the sample3 are not enough to determine is the samplecame from the suspectcame from the suspect
44--5, beyond a reasonable doubt5, beyond a reasonable doubt
5 very rare5 very rare
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National DNA Databank:National DNA Databank:
CODISCODIS TheThe COCOmbinedmbined DDNANA IIndexndex SSystemystem
Blends computer and DNA technologies into aBlends computer and DNA technologies into a
tool for fighting crimetool for fighting crime 2 indexes2 indexes
Convicted Offender IndexConvicted Offender Index DNA profiles of individuals convicted of criminal crimesDNA profiles of individuals convicted of criminal crimes
Forensic IndexForensic Index DNA profiles developed from crime scene evidenceDNA profiles developed from crime scene evidence
All profiles stored in CODIS are generatedAll profiles stored in CODIS are generatedusing STR analysisusing STR analysis
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The FutureThe Future
March 2004: President Bush proposedMarch 2004: President Bush proposed$1 billion in funding over the next 5 years$1 billion in funding over the next 5 years
Reduce DNA testing backlogReduce DNA testing backlog
Build crime lab capacityBuild crime lab capacity
Stimulate research and developmentStimulate research and development
Support trainingSupport training Protect the innocentProtect the innocent
Identify missing personsIdentify missing persons