DNA IdentificationDNA Identification

• Where does DNA come from?– 1/2 from mom– 1/2 from dad

• What is it?– “Blue print” of life

• How is DNA different among us?– Common vs Different

• What does “DNA” mean?– Deoxyribonucleic Acid

Cell Types

Where can DNA be found?Where can DNA be found?Where can DNA be found?Where can DNA be found?

Cell Blood

Sweat

Hair Roots Saliva

Various Tissue Semen

SAME

Types of objects where DNA may Types of objects where DNA may be foundbe found

Types of objects where DNA may Types of objects where DNA may be foundbe found

•Blood Stains

•Semen Stains

•Chewing Gum

•Stamps & Envelopes

•Penile Swabs

•Sweaty Clothing

•Bone

•Hair

•Fingernail Scrapings

•Saliva

Nucleus

Where is DNA in the body?Where is DNA in the body?Where is DNA in the body?Where is DNA in the body?

Cell

Nuclear DNA

Where types of DNA are found Where types of DNA are found in a cell?in a cell?

Where types of DNA are found Where types of DNA are found in a cell?in a cell?

Mitochondrial DNACellCell

MaternalChromosome

PaternalChromosome

Nucleus

Where is DNA in the body?Where is DNA in the body?Where is DNA in the body?Where is DNA in the body?

Where is DNA in the body?Where is DNA in the body?Where is DNA in the body?Where is DNA in the body?

Chromosome

DNA

A =Adenine

T =Thymine

G =Guanine

C =Cytosine

UnitsDouble Helix

GATC

DNA- What it looks likeDNA- What it looks likeDNA- What it looks likeDNA- What it looks like

Short Tandem Repeat

AGAT AGATAGAT

AGAT

AGAT

AGAT

AGAT

AGAT

AGAT

AGAT

6

4

DNA Profile =4,6

TCTA TCTA TCTA

TCTA

TCTA

TCTA

TCTA

TCTA

TCTA

TCTA

7

5

DNA Profile =5,7

TCTA

TCTA

STRSTR

BloodHair RootsSalivaSweatTissue

Chemical

DNA

Isolation of DNAIsolation of DNAIsolation of DNAIsolation of DNA

Semen stainChemical

RemoveEpithelial

DNA

Differential Isolation of DNADifferential Isolation of DNADifferential Isolation of DNADifferential Isolation of DNA

Different Chemical

Sperm DNA

Semen stain

Epithelial DNA

Sperm DNA

DNA

Solution

AmplificationAmplificationAmplificationAmplification(making copies)(making copies)(making copies)(making copies)

TG C

ATTA

G C

A T

A

G

TA

GA

A T

C

AT

CT

Heat

Step one of a single cycle

DENATUREDENATURE

TAC TA TTCTT AT C

AA TA G G

Step two of a single cycle

ANNEALANNEAL

Step three of a single cycle

TAAATA G G

T ACTT AT C TAC TT

CA

AA

G

GG

GT

TT

T

A G

EXTENDEXTEND

1 Cycle2 Cycles

3 Cycles

4 Cycles

5 Cycles

28 Cycles

AmplificationAmplificationAmplificationAmplification

DNA

PCR (Polymerase Chain Reaction)PCR (Polymerase Chain Reaction)PCR (Polymerase Chain Reaction)PCR (Polymerase Chain Reaction)

Analysis of amplified DNAAnalysis of amplified DNA Analysis of amplified DNAAnalysis of amplified DNA

AmplifiedDNA

DNAProfile

15,16 16,17 20,23 12,14 30,30X,Y 13.2,15Evidence

Area 1 Area 2 Area 3 Area 4 Area 5

AREAS OF DNA

SAMPLE Sex Area 6

Ref.Std.2

Ref.Std.1

15,16 16,17 20,23 12,14 30,30X,Y 13.2,15

14,15 17,18 23,24 13,13 30,30X,X 15,1914,15 17,18 23,24 13,13 30,30X,X 15,19

STR resultsSTR resultsThe DNA from the evidence stain and the reference sample from the suspect match.

The frequency of this matching pattern is approximately 1 in 520,000,000,000 in the Caucasian population, 1 in 618,500,000,000 in the African American population and 1 in 532,000,000,000 in the Hispanic population.Based on these results the suspect is the source of the evidence stain to a reasonable degree of scientific certainty.