Biology Project

ON
DNA FINGERPRINTING

A project submitted to the

RANI LAXMI BAI MEMORIAL SCHOOL

SECTOR-3, VIKAS NAGAR, LUCKNOW

Submitted by

SHASHWAT SHEKHAR SINGH

Class: XII - A3

Submitted to
Mrs. SHIKHA MA'AM

Teacher's signature Principal's signature

________________ ________________
 Acknowledgement
_________________________
At the outset, I would like to express my heartfelt gratitude

to the Almighty Lord for the divine guidance and wisdom

showered on me to undertake this project. I am immensely

grateful to my biology teacher for her guidance and support

to make this project a success. I am also thankful to my

parents for helping me in shaping out this project nicely.

Last but not the least I would like to thank my all

classmates who have helped me. Thank you to all.

SHASHWAT SHEKHAR SINGH

Class: - XII - A3
 Contents

What is DNA Fingerprinting?

Polymerase Chain Reactions
(PCR)
VNTRs

Gel electrophoresis

Southern Blotting
DNA fingerprinting
advantages
Forensic sciences
Famous cases solved by
DNA fingerprinting
Arbitrary
Bibliography
 What is DNA
fingerprinting? 3

DNA profiling (also called DNA fingerprinting, DNA

testing, or DNA typing) is a forensic technique used to
identify individuals by characteristics of their DNA. A DNA
profile is a small set of DNA variations that is very likely
to be different in all unrelated individuals, thereby being
as unique to individuals as are fingerprints (hence the
alternative name for the technique). DNA profiling should
not be confused with full genome sequencing. First
developed and used in 1984, DNA profiling is used in, for
example, parentage testing and criminal investigation, to
identify a person or to place a person at a crime scene,
techniques which are now employed globally in forensic
science to facilitate police detective work and help clarify
paternity and immigration disputes. DNA fingerprinting
has also been widely used in the study of animal and
floral populations and has revolutionized the fields of
zoology, botany, and agriculture.
Although 99.9% of human DNA sequences are the same
in every person, enough of the DNA is different that it is
possible to distinguish one individual from another, unless
they are monozygotic ("identical") twins. DNA profiling
uses repetitive ("repeat") sequences that are highly
variable, called variable number tandem repeats (VNTRs),
in particular short tandem repeats (STRs), also known as
microsatellites, and mini satellites. VNTR loci are very
similar between closely related individuals, but are so
variable that unrelated individuals are extremely unlikely
to have the same VNTRs.
 Polymerase Chain Reaction (PCR) 4

If there is only a small amount of DNA available for DNA

Fingerprinting the amount of DNA is increased by using
a technique called PCR. PCR is a method of DNA replication
in a test tube.

• Like All DNA Polymerases Taq polymerase can only add

to the 3’ end of an existing nucleotide
•A DNA primer that is complementary to the template is used
to supply that 3’ end
•

VNTRs
(variable
number
tandem

repeats) 5

• After we isolate the DNA and

amplify it with PCR
• We then treat the DNA with restriction enzymes
– cut DNA at specific sequences
 – Everyone’s DNA is different, so everyone’s DNA will
cut at different sites
• This results in different sized fragments

• The different sized fragments are called

restriction fragment length
polymorphisms, or RFLPs
• We can observe the
different sized fragments in
an experiment that
separates DNA based on
fragment size called Gel
Electrophoresis

• Everyone has genetic

sequences called variable
number tandem repeats, or
VNTRs
– Everyone has different
amounts of VNTRs
– The VNTRs make the different
sized RFLPs

Gel Electrophoresis 6

• Fragments of DNA from restriction enzyme cleavage

are separated from each other when they migrate
through a support called an agarose gel
– It is similar to the yummy food Jell-O gelatin
 – It is actually made out of some of the same
ingredients

• The size-based
separation of Molecules of DNA
separate based on size when an
electric current is applied to an agarose gel.

• This method is called gel electrophoresis

Gel Electrophoresis 7

• The separated DNA fragments are then drawn out of

the gel using a nylon membrane
• The nylon membrane is treated with chemicals that
break the hydrogen bonds in DNA and separate the
strands

• • The
single stranded DNA
is cross linked to the nylon membrane.
– By heat or UV light

• Incubate the nylon membrane with a radioactive

probe of single stranded DNA complementary to the
VNTRs.
 Gel Electrophoresis 8

• The radioactive probe shows up on photographic

film
– Because as it decays it gives off light
– The light leaves a dark spot on the film

• Different
individuals have different patterns
of bands
– These make up the fingerprint.

This Protocol is known as Southern Blotting.

Southern Blotting 9

A Southern blot is a method

used in molecular biology for
detection
of a specific DNA sequence in
DNA samples. Southern
blotting combines transfer
of electrophoresis-separated
DNA fragments to a filter
membrane and
subsequent fragment
detection by probe
hybridization.
 DNA Fingerprinting advantages: 10
• DNA fingerprints can be used to determine which
bone fragments belong to which individual

• DNA fingerprints of children should be similar to the

those
of parents. DNA fingerprinting can show which individuals
are the
parents of specific children.
 Forensic science 11

Forensic science is the application of science to

criminal and civil laws, mainly—on the criminal side—
during criminal investigation, as governed by the legal
standards of admissible
evidence and criminal
procedure.
Forensic scientists collect,
preserve, and analyze
scientific evidence during
the course of an
investigation. While some
forensic scientists travel to the scene of the crime to
collect the evidence themselves, others occupy a
laboratory role, performing analysis on objects brought
to them by other individuals.[1]
In addition to their
laboratory role,
forensic scientists
testify as expert
witnesses in both
criminal and civil
cases and can work
for either the
prosecution or the
defence. While any
field could technically be forensic, certain sections have
developed over time to encompass the majority of
forensically related cases.
Famous cases solved by DNA
fingerprinting
12

DNA Fingerprints, stray cigarette helped solve 1997 killing, sheriff

says
Amber Gail Creek, 14, was found dead in a Burlington marsh
Racine County Sheriff Christopher Schmaling on Tuesday identified
James P. Eaton as the 36-year-old Illinois man authorities suspect
killed Amber Gail Creek, a 14-year-old runaway girl from Illinois, in
1997. Credit: Racine County Sheriff’s Department
The 1997 killing of a 14-year-old girl whose body was found in a Racine
County marsh has been solved 17 years later with old fingerprints and
new DNA evidence unknowingly provided by the alleged
killer, the sheriff said Tuesday. Racine County Sheriff 13
Christopher
Schmaling identified the suspect as James P. Eaton, a 36-year-old
Illinois man, and said he is being held on $1 million bail in the death of
Amber Gail Creek, an Illinois runaway.
"Over the last 17 years we have dedicated thousands of investigative
hours to bring this tragic and senseless murder to its resolution,"
Schmaling told reporters at a news conference. "Today that day is
here."
The break in the case stemmed from fingerprints left on the black
plastic bag used to suffocate the teen, Schmaling said, and
investigators were able to track Eaton and pull DNA evidence off one
of his cigarettes. Eaton, a Palatine, Ill., resident, faces charges in
Racine County of first-degree intentional homicide and hiding a
corpse. Schmaling, who did not take questions from reporters, said
Amber's family has asked for privacy. Amber ran away from a state-
operated juvenile shelter in Chicago on Jan. 23, 1997. She attended a
party at a motel in Rolling Meadows, Ill., the week of her death and was
last seen leaving the party and getting into a luxury car with a man.
On Feb. 9, 1997, two men stumbled upon her body while they were
searching for hunting sites at the Karcher Wildlife Refuge in the Town
of Burlington.
She had been sexually assaulted, and her body was found posed with
an upraised hand and the greeting "HI" written on the back of her
hand, according to Journal Sentinel archives. She was found with a $5
price tag on her arm from a bookstore in the Schaumburg, Ill., area.
Investigators spent more than a year and a half examining
more than 1,300 missing persons files before they identified 14
her, and the case drew national attention at the time, including a
profile on "America's Most Wanted" that aired Dec. 12, 1998.
Fingerprints taken from the plastic bag and DNA evidence from
Amber's body initially yielded no matches, despite the help of the FBI
and agencies around the country.
Then this year, through new fingerprint identification technology used
by a crime lab in Oklahoma, authorities were able to match the prints
found on the plastic bag to Eaton's prints, Schmaling said. Eaton had
been fingerprinted in Illinois for past, minor offenses, but his name
previously had not come up in the Amber Creek case.
After learning of the fingerprint match on Feb. 28, Racine County
investigators conducted surveillance on Eaton for several days, and
when he dropped a cigarette while waiting for a train in the Chicago
area, they picked it up for DNA evidence.
It matched the DNA found on Amber's body, Schmaling said."Our sense
of accomplishment is tempered by the pain and loss we know Amber's
family continues to confront every day," Schmaling said. "Our
thoughts and prayers remain with Amber's father, mother, other family
and loved ones."
It wasn't clear whether Amber and Eaton knew each other or how they
first would have come into contact. Eaton was 19 at the time of the
killing.
The sheriff said investigators are still looking for people who can
provide with information in the case. They are encouraged to contact
the Racine County sheriff's office at (262) 636-3225 or leave an
anonymous tip at Crime Stoppers of Racine at (888) 636-9330.
 Arbitrary
15
It is the small difference in base pair sequences of DNA
that make the phenotypic appearance of each individual
unique. An easier and quicker solution to comparing
DNA sequences is DNA fingerprinting. In human beings,
ninety-nine per cent of DNA base sequences are
identical and are known as the bulk genomic DNA. The
remaining one per cent DNA base sequences differ and
are present as a small stretch of repeated sequences
known as repetitive DNA. DNA fingerprinting identifies
the differences in this region. To separate both genomic
as well as repetitive DNA the process of density
gradient centrifugation is carried out. As satellite DNA is
lighter and bulk DNA is heavier, so they get separated
on the basis of their density. Graphical representation
shows bulk genomic DNA as a major peak and repetitive
DNA as smaller peaks known as satellite DNA.
Satellite DNA is highly repetitive and consists of non-
coding sequences. Based on the length of the segment,
base composition and number of repetitive units
satellite DNA can be classified as mini-satellite DNA and
micro-satellite DNA. Mini-satellite is a section of DNA
which has a variable number of tandem repeats or
VNTR. This step is followed by the hybridisation of the
DNA fragments using a radio-labelled VNTR probe.
Finally, the hybridised DNA fragments are detected by a
technique called autoradiography conducted using an X-
ray film. Hybridisation with the VNTR probe results in an
autoradiogram, which produces several bands of
different sizes. These bands provide a characteristic
pattern to an individual’s DNA and vary from one
individual to another except in identical or monozygotic
twins. Today, 16
the accuracy of the DNA fingerprinting technique has
further improved due to the advent of the polymerase
chain reaction or PCR, where multiple copies of a single
DNA sequence can be made. DNA polymorphism is the
guiding principle behind genetic mapping and therefore
it helps in the DNA fingerprinting technique. The DNA
fingerprinting technique was developed by Alec
Jeffrey’s. DNA fingerprinting technique helps in crime
investigation, paternity testing, determining genetic
and population diversity and studying evolution and
speciation.

References
www.ncert.com

https://en.wikipedia.org

reference books
 BIBLIOGRAPHY

NCERT biology class 12

www.wikipedia.org

www.google.co.in

www.slideshare.net

www.biology.lifeeasy.org

www.biologyreference.com