dna fingerprinting project lead the way human body systems
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DNA DNA FingerprintingFingerprinting
Project Lead the WayProject Lead the Way
Human Body SystemsHuman Body Systems
Use of DNA to Determine Use of DNA to Determine IdentityIdentity
DNA controls production of proteinsDNA controls production of proteins Results in phenotype (eye color, facial Results in phenotype (eye color, facial
features)features) Contributes to structure and function Contributes to structure and function
DNA – 3 billion base pairsDNA – 3 billion base pairs No other person on planet has same code No other person on planet has same code
(except identical twins!)(except identical twins!) Only 0.1% of DNA differs from person to Only 0.1% of DNA differs from person to
personperson But the regions that do vary provide a true But the regions that do vary provide a true
genetic blueprintgenetic blueprint
Use of DNA to Determine Use of DNA to Determine IdentityIdentity
DNA obtained from DNA obtained from skeletal remainsskeletal remains
DNA purifiedDNA purified If degraded – If degraded –
amplified w/ PCRamplified w/ PCR
RFLPs compared to RFLPs compared to determine final determine final identity of missing identity of missing personperson
What are some sources of What are some sources of DNA Evidence?DNA Evidence?
Skin cellsSkin cells
HairHair
BloodBlood
SemenSemen
Anything with DNAAnything with DNA
DNA FingerprintingDNA Fingerprinting
AKA - DNA profiling analysis or DNA AKA - DNA profiling analysis or DNA typingtyping
Electrophoretic analysis of DNA Electrophoretic analysis of DNA fragment sizes generated by fragment sizes generated by restriction enzymesrestriction enzymes
Provides accurate, unambiguous Provides accurate, unambiguous identification of source DNA samplesidentification of source DNA samples
Restriction EnzymesRestriction Enzymes Endonucleases that Endonucleases that
cut phosphate bondscut phosphate bonds Break bonds between Break bonds between
deoxyribose and deoxyribose and phosphatephosphate
Attach to DNA and Attach to DNA and ““readread”” nucleotides nucleotides
Cut at specific Cut at specific sequencessequences
Over 3000 typesOver 3000 types
Restriction EnzymesRestriction Enzymes
Named after the organisms from Named after the organisms from which they were discovered / isolatedwhich they were discovered / isolated
Eco Eco RI – RI – Escherichia coliEscherichia coli RY13 RY13
HindHind III – III – Haemophilus influenzaeHaemophilus influenzae R4 R4
BamBam HI – HI – Bacillus amyloliquefaciensBacillus amyloliquefaciens HH
EcoEco RI Function RI Function
5` - G A A T T C – 3`3` - C T T A A G – 5`
Eco RI
5`- G A A T T C – 3`3` - C T T A A G – 5`
DNA fragments with “sticky” ends
Restriction EnzymesRestriction Enzymes
Forensic labs – use at least 2 restriction Forensic labs – use at least 2 restriction enzymesenzymes 4-base and 5-base (sometimes others)4-base and 5-base (sometimes others)
Size of DNA fragments – depends on Size of DNA fragments – depends on distance between recognition sitesdistance between recognition sites
Longer DNA molecule – the greater Longer DNA molecule – the greater probability that a specific recognition site probability that a specific recognition site will occurwill occur
Restriction EnzymesRestriction Enzymes Average human Average human
chromosome = 100 million chromosome = 100 million bpbp
Eco Eco RI – 6 bp recognition RI – 6 bp recognition sitesite
Probability – 1 site / 4096 Probability – 1 site / 4096 bpbp
Cut human DNA into Cut human DNA into ~25,000 fragments~25,000 fragments
Restriction EnzymesRestriction Enzymes
No two individuals have same pattern of No two individuals have same pattern of restriction enzyme recognition sitesrestriction enzyme recognition sites
Each person – unique genotype (different Each person – unique genotype (different alleles)alleles)
Mutations / Insertions / DeletionsMutations / Insertions / Deletions Changes distribution and frequency of Changes distribution and frequency of
restriction enzyme recognition sitesrestriction enzyme recognition sites
After Restriction DigestAfter Restriction Digest Analyze DNA fragments on agarose gelAnalyze DNA fragments on agarose gel
DNA fragments separated by molecular DNA fragments separated by molecular weight (size) due to net negative charge on weight (size) due to net negative charge on phosphatesphosphates
Restriction enzyme cleavage of relatively Restriction enzyme cleavage of relatively small DNA molecules – small DNA molecules – key to RFLP key to RFLP analysisanalysis
If DNA fragments are too large – canIf DNA fragments are too large – can’’t see t see RFLP patternRFLP pattern
Sample RFLP PatternsSample RFLP PatternsM
olec
ular
Mar
ker
Contr
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RFLP
Susp
ect R
FLP #
1
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FLP #
2
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FLP #
3
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FLP #
4
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FLP
#5
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P #6