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DNA. Three billion base pairs in DNA 99.5% similarity among individuals Genome = total DNA in the cell 5% of genome is encoded = serves as plans for protein synthesis 95% is non-encoded = JUNK ! Maybe…. Going to a certain Location (called a Locus) in your DNA…. We find: - PowerPoint PPT Presentation
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DNA• Three billion base pairs in DNA• 99.5% similarity among individuals• Genome = total DNA in the cell• 5% of genome is encoded = serves
as plans for protein synthesis• 95% is non-encoded = JUNK !
Maybe…
Going to a certain Location (called a Locus) in your
DNA…We find:
Short Tandem Repeats (STRs)3-7 bp long, repeating throughout a specific stretch of DNA at a particular location
AGTT AGTT AGTT AGTT AGTT AGTT
Technique of DNA Typing
Chain Reaction (PCR) and Short Tandem Repeats (STRs)
Please draw this!!
Intertwined strands of DNA representing segments of two chromosomes Chromosome segment on the left contains three repeating sequences of T–A–G
Chromosome segment on right has two repeating sequences of T–A–G
Variants of STR TH01Top DNA strand has six repeats of the STR A–A–T–GBottom DNA strand shows eight repeats
This person’s profile would read: TH01 ____ , ______
• http://wps.prenhall.com/wps/media/objects/3801/3892550/DNACD_mod02-1-12.swf
Process of DNA Typing
1. DNA Extraction2. Restriction Enzymes ------------>3. PCR – copy / amplify
-- Like your body does REPLICATION
4. Count the STRs at 13 locations in JUNK
5. Evaluation - Electropherogram
Genetic Analyzer• Alleles represented as peaks• Electropherogram: Graph representing STRs
Electropherogram
Statistical estimates: the product rule
0.222 x 0.222 x 2
= 0.1
www.bioforensics.com
Statistical estimates: the product rule
= 0.1
1 in 79,531,528,960,000,000
1 in 80 quadrillion
1 in 10 1 in 111 1 in 20
1 in 22,200
x x
1 in 100 1 in 14 1 in 81
1 in 113,400
x x
1 in 116 1 in 17 1 in 16
1 in 31,552
x x
www.bioforensics.com
Process of DNA Typing
http://wps.prenhall.com/wps/media/objects/3801/3892550/DNACD_mod04-2-11.2.swf
amelogenin
D19
D3
D8
TH01
VWA D21FGA
D16D18 D2
amelogeninD19
D3D8 TH01
VWA D21
FGA
D16D18 D2
Tw
o di
ffer
ent i
ndiv
idua
ls
DNA Size (base pairs)
Results obtained in less than 5 hours with a spot of blood the size of a pinhead
probability of a random match: ~1 in 3 trillion
Human Identity Testing using STRs
Simultaneous Analysis of 10 STRs and Gender ID
http://wps.prenhall.com/wps/media/objects/3801/3892550/DNACD_mod04-2-11.2.swf
Who’s your Daddy?Paternity testing
• ABO blood typing-exclude paternity, but cannot confirm paternity
• DNA testing can confirm paternity
STR Profiling Sensitivity
• STR Profiling-can detect 125 picograms
• 1 picogram = one-trillionth of a gram• One cell has 7 picograms of DNA• 18 DNA bearing cells are needed to
get a STR profile
