Dna Fingerprinting

Forensic science

(often shortened to

forensics) is the

application of a broad

spectrum of sciences to

answer questions of

interest to a legal system

BIOMETRICS

- a science that uses people's physical characteristics

to identify them

Finger print

Eye scan

Voice fingerprints

DNA fingerprints

Fingerprinting

D N A:

A:

THE MODERN FINGERPRINT

The Forest Hills Rapist

• First use of DNA evidence in the US

• In 1988, Victor Lopez was tried for the sexual

assault of three women

• All the women said their attacker was black

• However, Lopez’s blood was tested against

sperm left at the scene and found to be a

match.

• Despite the eyewitness testimony, Lopez was

found guilty

The O.J. Simpson Case

The OJ Simpson Case

•Nicole Brown Simpson and her friend Ronald Goldman were murdered at

her Los Angeles home on June 12, 1994.

•The prime suspect was her ex-husband, and former NFL star, O.J. Simpson

•Forty five samples were collected and it was discovered that the DNA

found

found at the crime scene was that of O.J. Simpson

•Defense attorneys attacked procedures used in collecting the DNA.

•The defense alleged that contamination could have occurred; at one

point one witness admitted to mislabeling a sample.

•This created enough doubt in the jury’s eyes, which led to Simpson being

found not guilty.

DNA:

DNA: the genetic material

- deoxyribonucleic acid

(DNA)

- guides transcription

and translation of

proteins

- composed of 4 bases:

Adenine (A), thymine (T),

Cytosine (C), guanine (G)

DNA Fingerprinting

Determination of an individual’s unique

collection of DNA patterns / sequences

How to do DNA Fingerprinting

The Big Picture

Collect Tissue Sample

>1000 cells

RFLP / Southern blot

> 20 cells

PCR Analysis

Restriction enzymes

- Occur naturally in bacteria

- Hundreds are purified and available commercially

- Named for bacterial genus, species, strain, and type

- Recognize specific base...