This document provides information about DNA fingerprinting. It begins with the structure of DNA and how it is uniquely arranged in each individual. It then discusses how DNA fingerprinting works, including the steps of extraction, multiplication, fragmentation, probing, separation, and interpretation to generate DNA profiles for identification comparisons. Examples are given of how DNA fingerprinting can be used in criminal investigations and other forensic applications like determining paternity. The central dogma of biology relating DNA to RNA and proteins is also summarized.

1. 1
DNA
Finger Printing
I – Introduction to Genetics
II – DNA Fingerprinting
By: Prof. Mayank David Raiborde

2. FACTS ABOUT DNA
• DNA stands for
Deoxyribo Nucleic Acid
• Every living thing including
animals has DNA
• DNA is not as unique as we
think they are. The chances
of two people having
exactly the same DNA
profile is 30,000 million to 1
(except for identical twins).
MAN
TISSUES
CELLS
NUCLEUS
DNA
GENES
CHROMOSOME

4. DNA- UNRAVELED
Nitrogenous
Base Ribose Sugar Nucleoside
Nucleoside
Phosphate
Group
Nucleotide

5. O
O=P-O
O
Phosphate
Group
N
Nitrogenous base
(A, G, C, or T)
CH2
O
C1
C4
C3 C2
5
Sugar
(deoxyribose)
STRUCTURE OF DNA

7. Chargaff’s Rule
• Adenine must pair with Thymine
• Guanine must pair with Cytosine
• Their amounts in a given DNA molecule will be
the same.
G C
T A

8. O
O=P-O
O
Phosphate
Group
N
Nitrogenous base
(A, G, C, or T)
CH2
O
C1
C4
C3 C2
5
Sugar
(deoxyribose)
STRUCTURE OF DNA

9. Debate
GMO’s – Good or Bad
Good –
Bad –
Seminars
1. Role of mitochondrial DNA in FS –
2. The Human Genome project –
3. Chromosomes -

10. The ends of a DNA molecule are
called 3' and 5' ends, based on the
numbering of carbon atoms in the
deoxyribose sugars. One end of the
chain carries a free phosphate group
is attached to the 3'-carbon atom; this
is called the 3' end of the molecule.
The other end of the free phosphate
group is attached to the 5'-carbon
atom; this is called the 5' end of the
molecule.

11. DOUBLE HELIX STRUCTURE
 The double-helix model of DNA
structure was first published in the
journal Nature by JAMES D. WATSON
and FRANCIS CRICK in 1953
Crick, Wilkins and Watson each
received one third of the 1962 Nobel
Prize in Physiology or Medicine for
their contributions to the discovery

12. TRIVIA
In a blood sample, where will
you find DNA?
1. RBC’s
2. WBC’s
3. Platelets
4. Plasma

13. CENTRAL DOGMA
Formulated by Francis Crick, 1958

14. DNA in Forensic Science
•The chemical structure of everyone's
DNA is the same.
•The only difference between
individuals is the order of the base
pairs.
•This can give the valuable
information to distinguish the
individuals.
•So plays an important role in forensic
investigations

15. Invention
• The process of DNA fingerprinting was invented
by Sir Alec Jeffreys at the University of Leicester
in 1985.
• He was knighted in 1994.

16. USEFUL Vs JUNK DNA
• The entire DNA is still being studied. – The
World Genome Project.
• Only 1.02% of DNA has been medically
explained.
• Rest of the 98.98% DNA is still unravelled. –
Junk DNA.
• While this is a medical understanding of DNA.
Forensically we have better use for the junk
DNA.
• Portions of junk DNA too have repeat tandems
which are forensically significant.

17. SINGLE TANDEM REPEAT

22. TRIVIA
By DNA study can you
differentiate / identify the
following:
1. Age?
2. Race?
3. Sex?

23. Applications of DNA Fingerprinting
DNA FP
Baby Exchange
Rape
Paternity
Crime
Investigation Identification
Mass Disaster
Migration
Diversity
Family tree
Wildlife Genomics

24. Steps of DNA Finger Printing
1.Extraction
2.Multiplication
3.Fragmentation
4.Probing
5.Separation
6.Interpretation

26. • Blood
• Semen
• Saliva
• Hair
• Skin cells
• Bone
• Teeth
• Tissue
• Urine
• Feces
• Vomit
Condoms
Envelopes
Hat bands
Cigarette Butts
Chewing gum
Drinking Cups
Under victim’s fingernails
Sources of Biological Evidence

27. EXTRACTION

28. MULTIPLICATION

29. FRAGMENTATION

30. PROBING

31. SEPARATION

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

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

37. Instrumentation
Thermal Cycler
Picodrop
DNA Extraction Machine
Genetic Analyzer
Electrophoresis
RT PCR

45. MODERN FORMS OF DNA
FINGERPRINTNG
1.STR Analysis
2.RFLP - Restriction Fragment Length
Polymorphism
3.AFLP - Amplified Fragment Length
Polymorphisms
4.Y Chromosome analysis
5.RT-PCR - Reverse Transcription Polymérase
Chain Réaction

46. CASE HISTORY
• 1983 -- A controversial godman – from Sri Lanka –
set up an ashram in Pudukottai, TN.
• Accused of sexually abusing women inmates of the
ashram – impregnating them – and later aborting
their pregnancies – to hide the crime.
• 1994 - Arul Jyoti, 19/F escaped to Chennai and
lodged complaint – she was pregnant and wanted
abortion – CBI-CID, T took up the case in 1995
• Prosecution chose to go for DNA analysis – one of
the 1st in India. DNA of accused, victim and aborted
fetus were studied.
• DNA study done at CCMB, Hyderabad (Today’s
CDFD)

48. • Defense requested re-examination, which the
Sessions court allowed.
• A London-based British expert was given the task of
re-examination.
• 1997 – Defense proved the theory to be wrong and
alleged the CCMB of malpractise.
• Dr. Lalji Singh, Head of CCMB gave expert witness
and claimed that 13 STR’s were studied by CCMB
whereas the defense had studied only 6 STR’s as
basis of which 1 was for sex identification.
• Sessions court found the accused to be guilty and
ordered double life imprisonment and Rs. 6.64
million fine.
• The godman died during prison-time.

49. DNA – Legal issues
X
DNA – Ethical issues

50. DNA PROFILING BILL

51. 51
DNA, RNA & PROTEINS
The molecules of life

52. Today…
• DNA structure and replication
• RNA
– Transcription
– Translation
• Protein synthesis
– Amino acids

53. DNA
• Deoxyribonucleic Acid (DNA)
• is the blueprint for life:
• contains __________________________

54. DNA structure
• DNA is a polymer of
nucleotides
Each nucleotide composed of
_________________
_________________
_________________

55. Four DNA bases
• Four kinds of nitrogenous bases:
• Purine bases
• Pyrimidine bases

56. DNA: Complimentary base pairing
• Adenine pairs with ________
A
• Cytosine pairs with _________
C

57. DNA STRUCTURE
• DNA is a ________ helix
• Discovered by
Watson and Crick, 1953

58. DNA REPLICATION
(in the nucleus)
• Each DNA strand
becomes a _____________,
parent strand becomes apart
• Proper base-pairs are
assembled on that template

59. DNA replication
• Nucleotides are connected together to make
a new strand that is ____________ to the old
strand.
• The new double strand is
_________ to the old double strand
• This is called ________________________
replication

60. A-T vs. G-C bond
• A-T is a double bond…
• C-G is a ______ bond (stronger)…
• DNA double strand can separate into 2 single
strands when heated.
• Which strand would require more heat (more
energy) to separate: an A-T rich or a C-G rich
double strand?

61. RNA structure and synthesis
• RNA: ___________________
• Is very similar to DNA
(repeating subunits, nucleotides).
• Difference between RNA and DNA:
Each nucleotide contains a different sugar:
____________ instead of deoxyribose.
Bases are A, G, C, and U (_________________)
A pairs with ______; G pairs with ______

62. RNA
• RNA is _________ stranded
and shorter
• RNA is less stable than DNA:
RNA doesn’t persist in the cell for long
(sometimes it exists for a few seconds),
whereas DNA can persist for the life of the
cell.

63. CENTRAL DOGMA
DNA
RNA
Proteins
• 3 different RNA molecules involved in protein
synthesis: mRNA, rRNA, ______
• TRANSCRIPTION: RNA synthesis from DNA.
transcription
translation

64. Transcription: DNA  RNA
• Transcription occurs in the _________
• mRNA carries the message about what type of
protein to make from the DNA in the nucleus to the
ribosome
• The nucleotide sequences of RNA and DNA are the
same (except in RNA _______ is used instead of
thymine)
• mRNA is synthesized from DNA using base pairing
• DNA unwinds in a section

65. • RNA ___________ attaches at the promoter
sequence of DNA, and it moves along the DNA,
unzipping the strands – this allows for one mRNA
molecule to be formed.
• During ______________, a molecule of messenger
RNA is formed as a complementary copy of a
region on one strand of the DNA molecule

66. Transcription
• Once mRNA is formed, enzymes in the nucleus
remove the
• Introns ________________ and leave the
• Exons _________________

67. The Genetic Code
• Each 3 consecutive bases on the mRNA is a code
word, codon, that specifies an amino acid.
• The genetic code consists of _____codons,
• but only ____ code amino acids.
• Three codons act as
signal terminators
(_____,______,______)
• One codon, AUG, codes
for methionine, and is also
the _______ signal for translation.

68. 20 Amino Acids
There are ____ amino
acids – they are like
the ‘bricks’, or
building blocks
to make
all ________

69. Translation: RNA  Protein
• Translation: synthesizing a _________ from
amino acids, according to the sequences of the
nucleotides in mRNA.
• Occurs at the __________, in cytoplasm of cell
• Ribosomal RNA, rRNA, is needed for protein
synthesis – helps mRNA bind to the _________
• ___________ RNA, tRNA, brings specific amino
acids to the ribosome to be assembled as
proteins.

70. Translation
• ___________ RNA, rRNA, joins with a number
of proteins to form ribosomes
• Ribosomes are the sites of ______________
• Ribosomes consist of
a large subunit and
a small subunit.
mRNA binds to the
_______ subunit.

71. Transfer RNA (tRNA)
• Transport molecule
that carries specific
_____________ to a
ribosome
(80 nucleotides long)
• Folded
• Each tRNA recognizes
the correct codon on
the mRNA molecule

72. Translation

73. Steps in Translation
1. mRNA leaves the nucleus and migrates to
ribosome
2. mRNA binds to small ribosomal subunit
3. tRNA brings an amino acid to the ribosome,
where anticodon on the tRNA binds to the codon
of the mRNA
4. The amino acid bonds to its adjoining amino acid
to form a growing polypeptide molecule
5. The tRNA without the amino acid is released from
the ribosome
6. Other tRNA’s bring amino acids to the ribosome
to complete the protein molecule

74. Protein translation

75. Protein synthesis
• Occurs in the cytoplasm of the cell

76. Protein synthesis
• Amino acids are the repeating sub-units of
protein molecules.
• Amino acid order determines the protein
• ____ amino acids exist in all life forms
• ______of amino acids is important, determines
the 3-dimensional shape of the molecule.
• Structure of the protein determines its ______

77. Proteins
• Biological activity (function) of proteins depends
largely on its 3-D structure

78. Summary:

79. Genomic
Geography
• In Cell Nucleus: RNA is produced by transcription.
• RNA is single-stranded; substitutes the sugar ribose for deoxyribose and the base uracil for
thymine
• Messenger RNA or mRNA, conveys the DNA recipe for protein synthesis to the cell cytoplasm.
• mRNA binds to ribosome, each three-base codon of the mRNA links to a specific form of
transfer RNA (tRNA) containing the complementary three-base sequence.
• This tRNA, in turn, transfers a single amino acid to a growing protein chain.
• Each codon directs the addition of one amino acid to the protein. Note: the same amino acid can
be added by different codons; in this illustration, the mRNA sequences GCA and GCC are both
specifying the addition of the amino acid alanine (Ala).

80. Important
• Both DNA and RNA have a direction: one end
is the 3’ the other is the 5’ end.
• Thus, codons are read in one direction only.
• Also, note there is redundancy in the genetic
code: the different sequences can specify for
the same amino acid.
Example: _______________= Leucine

81. When things go wrong…
• Mutations: changes in the DNA sequence, that
may be passed along to future generations.
• Point mutations: a single base substitution
THE CAT SAW THE RAT
THE CAT SAW THE HAT
• Deletion: a small DNA segment is lost
• Insertion: a segment of DNA is added
• Frame-shift mutation: modification of the reading
frame after a deletion or insertion, resulting in all
codons downstreams being different.

82. Somatic Mutations
• ___________ mutations: occur in body cells, or
cells that do not lead to gametes.
• Somatic mutations that occur in leaves, roots or
stems are usually not passed on to future
generations…
• UNLESS the plant reproduces ____________

83. Terminologies / Concepts
• DNA
• RNA
• Replication
• Restriction
• Ligase enzyme
• Central dogma
• Complementary
• Transcription
• Translation
• Ribosome
• Histone
• Mutation
• Aberration
• Amino acid
• Protein
• Photo 51
• Watson and Crick model
• Cloning