Dna fingerprinting powerpoint

1. DNA ProfilingDNA Profiling
(DNA fingerprinting)(DNA fingerprinting)

2. What is DNA Profiling?What is DNA Profiling?
A technique used by scientists to A technique used by scientists to
distinguish between individuals of the distinguish between individuals of the
same species using only samples of their same species using only samples of their
DNA. DNA. The only difference between people The only difference between people
(or any animal) is the order of the (or any animal) is the order of the
base pairsbase pairs. The information contained in . The information contained in
DNA is determined primarily by the DNA is determined primarily by the
sequence of letters along the zipper. The sequence of letters along the zipper. The
different sequences is the same as the different sequences is the same as the
word "POST" has a different meaning word "POST" has a different meaning
from "STOP" or "POTS," even though from "STOP" or "POTS," even though
they use the same lettersthey use the same letters

3. 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.

4. Stages of DNA ProfilingStages of DNA Profiling
Stage 1Stage 1::
Cells are broken downCells are broken down
to release DNAto release DNA
If only a small amount If only a small amount
of DNA is available it of DNA is available it
can be amplified using can be amplified using
the polymerase chain the polymerase chain
reaction (PCR)reaction (PCR)

5. Stages of DNA Profiling Stages of DNA Profiling
Step 2:Step 2:
The DNA is cut into fragments using The DNA is cut into fragments using restriction restriction
enzymesenzymes..
Each restriction enzyme cuts DNA at a specific base Each restriction enzyme cuts DNA at a specific base
sequence.sequence.

6. Stages of DNA ProfilingStages of DNA Profiling
The sections of DNA that are cut out The sections of DNA that are cut out
are called are called restriction fragments. restriction fragments.
This yields thousands of restriction This yields thousands of restriction
fragments of all different sizes fragments of all different sizes
because the base sequences being because the base sequences being
cut may be far apart (long fragment) cut may be far apart (long fragment)
or close together (short fragment).or close together (short fragment).

7. Stages of DNA ProfilingStages of DNA Profiling
Stage 3:Stage 3:
Fragments are Fragments are
separated on the separated on the
basis of size using basis of size using
a process called a process called gel gel
electrophoresis.electrophoresis.
DNA fragments are DNA fragments are
injected into wells injected into wells
and an electric and an electric
current is applied current is applied
along the gel. along the gel.

8. Stages of DNA ProfilingStages of DNA Profiling
DNA is negatively DNA is negatively
charged so it is charged so it is
attracted to the attracted to the
positive end of the positive end of the
gel.gel.
The shorter DNA The shorter DNA
fragments move fragments move
faster than the faster than the
longer fragments. longer fragments.
DNA is separated on DNA is separated on
basis of size.basis of size.

9. Stages of DNA ProfilingStages of DNA Profiling
A radioactive material A radioactive material
is added which is added which
combines with the DNA combines with the DNA
fragments to produce a fragments to produce a
fluorescent image.fluorescent image.
A photographic copy of A photographic copy of
the DNA bands is the DNA bands is
obtained.obtained.

10. Stages of DNA ProfilingStages of DNA Profiling
Stage 4:Stage 4:
The pattern of fragment distribution The pattern of fragment distribution
is then analysed.is then analysed.

11. Uses of DNA ProfilingUses of DNA Profiling
DNA profiling is DNA profiling is
used to solve used to solve
crimes crimes and and
medical medical
problemsproblems

12. CrimeCrime
Forensic science is the use of Forensic science is the use of
scientific knowledge in legal scientific knowledge in legal
situations.situations.
The DNA profile of each individual is The DNA profile of each individual is
highly specific.highly specific.
The chances of two people having The chances of two people having
exactlyexactly the same DNA profile is the same DNA profile is
30,000 million to 1 (except for 30,000 million to 1 (except for
identical twins). identical twins).

13. Biological materials used for DNA Biological materials used for DNA
profilingprofiling
BloodBlood
HairHair
SalivaSaliva
SemenSemen
Body tissue cellsBody tissue cells
DNA samples have DNA samples have
been obtained from been obtained from
vaginal cells vaginal cells
transferred to the transferred to the
outside of a condom outside of a condom
during sexual during sexual
intercourse.intercourse.

14. DNA Profiling can solve crimesDNA Profiling can solve crimes
The pattern of the DNA profile is then The pattern of the DNA profile is then
compared with those of the victim and the compared with those of the victim and the
suspect.suspect.
If the profile If the profile matchesmatches the suspect it the suspect it
provides strong evidence that the suspect provides strong evidence that the suspect
was present at the crime scene (was present at the crime scene (NB:it NB:it
does not prove they committed the does not prove they committed the
crime).crime).
If the profile If the profile doesn’tdoesn’t match the suspect match the suspect
then that suspect may be eliminated from then that suspect may be eliminated from
the enquiry.the enquiry.

15. 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:

16. Was the suspect at the crime scene?Was the suspect at the crime scene?
Suspects
Profile
Blood sample
from crime
scene
Victims
profile

17. Solving Medical ProblemsSolving Medical Problems
DNA profiles can be used to determine DNA profiles can be used to determine
whether a particular person is the parent whether a particular person is the parent
of a child.of a child.
A childs paternity (father) and A childs paternity (father) and
maternity(mother) can be determined.maternity(mother) can be determined.
This information can be used inThis information can be used in
•Paternity suitsPaternity suits
•Inheritance casesInheritance cases
•Immigration casesImmigration cases

18. 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.

19. Is this man the father of the child?Is this man the father of the child?
Mother Child Man

20. Personal IdentificationPersonal Identification
The notion of using DNA fingerprints as a sort The notion of using DNA fingerprints as a sort
of genetic bar code to of genetic bar code to identify individualsidentify individuals has has
been discussed been discussed
Diagnosis of Inherited DisordersDiagnosis of Inherited Disorders
diagnosis inherited disordersdiagnosis inherited disorders in both in both prenatalprenatal
and and newborn babiesnewborn babies
These disorders may include cystic fibrosis, These disorders may include cystic fibrosis,
hemophilia, Huntington's disease, familial hemophilia, Huntington's disease, familial
Alzheimer's, sickle cell anemia, thalassemia, Alzheimer's, sickle cell anemia, thalassemia,
and many others. and many others.

21. In 2002 Elizabeth In 2002 Elizabeth
Hurley used DNA Hurley used DNA
profiling to prove profiling to prove
that Steve Bing that Steve Bing
was the father was the father
of her child Damienof her child Damien

22. DNA Fingerprinting using VNTR'sDNA Fingerprinting using VNTR's
On some human chromosomes, a short sequence of On some human chromosomes, a short sequence of
DNA has been repeated a number of times. DNA has been repeated a number of times.
 the repeat number may vary from one to thirty repeats the repeat number may vary from one to thirty repeats
these repeat regions are usually bounded by specific these repeat regions are usually bounded by specific
restriction enzyme sites restriction enzyme sites
cut out the segment of the chromosome containing cut out the segment of the chromosome containing
this this variable number of tandem repeatsvariable number of tandem repeats ( (VNTR'sVNTR's ) )
identify the VNTR's for the DNA sequence of the identify the VNTR's for the DNA sequence of the
repeat. repeat.

23. Famous CasesFamous Cases
Colin Pitchfork was Colin Pitchfork was
the first criminal the first criminal
caught based on caught based on
DNA fingerprinting DNA fingerprinting
evidence. evidence.
He was arrested in He was arrested in
1986 for the rape 1986 for the rape
and murder of two and murder of two
girls and was girls and was
sentenced in 1988. sentenced in 1988.