WHAT IS DNA FINGERPRINTING?

DEFINITION OF DNA FINGERPRINTING Person’s unique

identifier Scientific

technique of taking a cell and comparing it

95.5% of DNA is the same, it is the 4.5% that isn’t the same

DNA FINGERPRINTING Can tell if

samples are from The same personRelated personNon-related

person Get a Certain

Probability Match

HOW IS DNA FINGERPRINTING CONNECTED WITH GENETICS?

What is DNA? Chemical Structure Chromosomes Double Helix Base Strands of DNA are connected

HISTORY Research Began in

the late 70’s early 80’s

Alec Jeffreys DNA sequence not

different but the number of times it is repeated

September 10th, 1984

Sir Alec Jeffreys

4 STAGES OF DNA FINGERPRINTING

STAGES OF DNA FINGERPRINTING Stage 1: Cells are broken down to release DNA

If only a small amount of DNA is available it can be amplified by using a polymerase chain reaction (PCR)

STAGES OF DNA FINGERPRINTING Stage 2:

The DNA is then cut into little fragments using restriction enzymes.

Each restriction enzyme cuts DNA at a specific base sequence.

For example:

STAGES OF DNA FINGERPRINTING

This creates thousands of restriction fragments of all different sizes because the base sequences being cut may be far apart (long fragment) or close together (short fragment).

STAGES OF DNA FINGERPRINTINGStage 3: Fragments are then

separated by size using a process called gel electrophoresis.

The DNA is then injected into wells and an electric current is applied along the opposite sides of the gel.

STAGES OF DNA FINGERPRINTING DNA is negatively

charged so it is attracted to the positive end of the gel.

The shorter DNA fragments move faster than the longer fragments so they travel deeper into the gel.

STAGES OF DNA FINGERPRINTING A radioactive

material is added to combines with the DNA fragments that makes them show up on a nylon sheet.

This makes a photographic copy of the DNA bands.

STAGES OF DNA FINGERPRINTINGStage 4: The pattern of the fragment distribution

is then analysed and compared.

CONTROVERSIES

SURROUNDING DNA

FINGERPRINTING

SCIENTIFIC SCRUTINY DNA fingerprinting was introduced into

the courts in the US in 1988.

DNA typing was considered flawed from the beginning because the companies had no track record within the forensic field.

Several early cases had poorly defined procedures and useless interpretations of the evidence.

(Lander and Budowle)

“MATCHING MISHAPS” “CSI Belief System”

If the DNA of the suspect and the DNA evidence appear sufficiently similar the samples are declared a match.

If any of the fragments are separated by more than three standard deviations of the measurement, it is declared a non-match and the donor is released from the suspect list (Roeder).

FAKED EVIDENCE Nucleix; an Israeli

group of scientists revealed through their published work in a forensics journal that they successfully took blood and saliva from one individual and was able to replace it with different DNA samples from another donor.

How?

They extracted the white blood cells (containing the DNA) and left the red blood cells, and added amplified DNA from another donor…

RESULTS?They sent the sample they created to a

well-known forensics lab in the United States and when it was analyzed as a normal sample

They were unaware and unable to tell it had been modified in any way

Nucleix is now promoting a test designed to tell the difference between real and faked/modified DNA samples.

(Arnold)

BENEFITS AND NEGATIVE IMPACTS

ETHICAL, LEGAL, AND SOCIAL CONCERNS

Privacy: Increases genetic discrimination by:

Government Insurers Employers Schools Banks & others

Practicality:Backlog of over half a million DNA samples

wait to be entered into he CODIS system

ETHICAL, LEGAL, AND SOCIAL CONCERNS (CONT.) Who is chosen for sampling?

United States - Each state legislature independently decides whether DNA can be sampled for arrestees or convicts.

Katie’s Bill – New Mexico, 2006 Previous Law: Only required DNA from convicted

felons New Law: Requires police to take DNA samples

from suspects in most felony arrests Fourth Amendment violation?

Civil liberties advocates says violations against unreasonable search and seizure

Stressed law could be abused to justify arrests made on less than probable cause just to obtain DNA evidence.

ETHICAL, LEGAL, AND SOCIAL CONCERNS (CONT.)

As of September 2007: All 50 states: Require convicted sex offenders

to submit DNA. 44 states: Require convicted felons to submit

DNA 9 states: Require DNA samples from those

convicted of certain misdemeanors 11 states: Laws authorizing arrestee DNA

sampling Alaska, Arizona, California, Kansas, Louisiana,

Minnesota, New Mexico, N. Dakota, Tennessee, Texas, & Virginia

POTENTIAL BENEFITS Major crimes are often committed by people

with other offenses. DNA bank makes it easier to find suspects.

Innocent people are being incarcerated for crimes they didn’t commit. DNA being taken at the time of the arrest may have proven them innocent by now.

DNA banking from arrestees’ results in financial savings in: investigation, prosecution, and incarceration.

NEGATIVE IMPACTS Arrestees found innocent of crimes &

the retention of their DNA raises ethical & social issues.

People may be identified as matches or partial matches to DNA found at crime scenes if they were there earlier or have similar DNA profile to actual criminal.

NEGATIVE IMPACTS (CONT.)

Sensitive genetic information can be obtained from DNA samples. Police & other officials would have access to the people’s DNA without their consent.Seen as intrusion of personal privacy and a

violation of civil liberties.

Even the most secure database has a chance of being compromised.

BIBLIOGRAPHY

Human Genome Project Information. 16 June 2009. 21 February 2011 <http://www.ornl.gov/sci/techresources/Human_Genome/elsi/forensics.shtml>.

U.S. Citizenship and Immigration Services. 13 January 2011. 21 February 2011 <http://www.uscis.gov/portal/site/uscis/menuitem.eb1d4c2a3e5b9ac89243c6a7543f6d1a/?vgnextoid=b6629c7755cb9010VgnVCM10000045f3d6a1RCRD&vgnextchannel=b6629c7755cb9010VgnVCM10000045f3d6a1RCRD>.

Arnold, Paul. "Who Invented DNA Fingerprinting?" 22 July 2010. BrightHub. 22 February 2011 <http://www.brighthub.com/science/genetics/articles/14458.aspx>.

  Lieberman, Kate Brinton and Kim-An. "Basics of DNA Fingerprinting." 1994.

Protist Biology Washington. 22 February 2011 <http://protist.biology.washington.edu/fingerprint/dnaintro.html>.

McGuigan ,Brendan. " What Is DNA Fingerprinting?" 15 February 2009. Wisegeek. 24 February 2011 < http://www.wisegeek.com/what-is-dna-fingerprinting.htm>.