DNA ProfilingDNA Profiling

(DNA fingerprinting)(DNA fingerprinting)

What is DNA Profiling?What is DNA Profiling?

A technique used by scientists to A technique used by scientists to distinguish between individuals of distinguish between individuals of

the same species using only samples the same species using only samples of their DNA of their DNA

Who Invented it?Who Invented it?

The process of DNA The process of DNA fingerprinting was fingerprinting was invented by Alec invented by Alec Jeffreys at the Jeffreys at the University of University of Leicester in 1985. Leicester in 1985.

He was knighted in He was knighted in 1994.1994.

Stages of DNA ProfilingStages of DNA Profiling DNA in Cells is broken down into DNA in Cells is broken down into

fragmentsfragments

Fragments are separated using a Fragments are separated using a

process called process called gel gel electrophoresis.electrophoresis.

The shorter DNA fragments move The shorter DNA fragments move faster than the longer fragments. faster than the longer fragments.

(DNA is separated on basis of size.)(DNA is separated on basis of size.)

Stages of DNA ProfilingStages of DNA Profiling

A radioactive A radioactive material is added material is added which combines which combines with the DNA with the DNA fragments to fragments to produce a produce a fluorescent image.fluorescent image.

A photographic A photographic copy of the DNA copy of the DNA bands is obtained.bands is obtained.

ExampleExample

A violent murder occurred. A violent murder occurred. The forensics team retrieved a blood The forensics team retrieved a blood

sample from the crime scene. sample from the crime scene. They prepared DNA profiles of the They prepared DNA profiles of the

blood sample, the victim and a blood sample, the victim and a suspect as follows:suspect as follows:

Was the suspect at the crime Was the suspect at the crime scene?scene?

Suspects Profile

Blood sample from crime scene

Victims profile

Example: A Paternity TestExample: A Paternity Test

By comparing the DNA profile of a By comparing the DNA profile of a

mother and her child it is possible tomother and her child it is possible to

identify DNA fragments in the child identify DNA fragments in the child

which are absent from the mother and which are absent from the mother and

must therefore have been inherited must therefore have been inherited

from the biological father.from the biological father.

Is this man the father of the child?Is this man the father of the child?

Mother Child Man

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