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8/9/2019 Introduction to DNA Rizwan
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DNA stands for deoxyribonucleic acid
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Structure of DNA
DNA exist in the form of a twisted
double helix and governs various
inheritance traits
Length of DNA in a cell is 180cm.
Each chromosome consist of two
DNA molecules.
Each DNA molecule is hydrogen
bonded
Nuclear protein called histones ,
the complex of DNA and histones
being referred to as chromatin,
structurally stabilize the helix.
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STRUCTURE OF DNA
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Each nucleotide is
composed of phosphate,
deoxyriboes sugar, and
organic nitrogenousbases, such as adenine
(A), guanine (G), cytosin
(C), thiamine (T).
DNA molecule resembles
a twisted loop ladder withfour kinds of stair-steps,
A-T , T-A , C-G or G-C
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A
P
s
P
P
s
Ps
P
s
P
s
P
s
P
s
P
s
P
s
P
P
s
P
s
s
P
s = Sugar
= Phosphate
AC
GT
CG
T
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A =Adenine
T =Thymine
G =Guanine
C =Cytosine
UnitsDouble Helix
GAT
C
DNA- What it looks likeDNA- What it looks like
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DNA is Blueprint
of
Life
GENETIC LANGUAGE
A Z 26 LETTERS
37 LETTERS
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BOOK OF LIFE 3.2 BILION LETTERS IN
HUMAN DNA
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BOOKCHAPT
ERS paragraph sentence Word letter
Human cell nucleus chrompsomes Locii (gene) DNA
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Chromosomes Exist in pairs
Father Mother
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1 2 3 4 5 6 7 8
9 10 11 12 13 14 15 16
17 18 19 20 21 22 X Y
CHROMOSOMESCHROMOSOMES
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CHROMOSOMES
FOR NORMAL
HUMAN BEINGS
CHROMOSOMES
FOR NORMAL
HUMAN BEINGS
4646
FATHERFATHER
46 CHROMOSOMES46 CHROMOSOMES
MOTHERMOTHER
46 CHROMOSOMES46 CHROMOSOMES
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Q) What does DNA mean?Q) What does DNA mean?
A) Deoxyribonucleic AcidA) Deoxyribonucleic Acid
Q) Where does DNA come
Q) Where does DNA comefrom?from?
A) 1/2 from momA) 1/2 from mom
A) 1/2 from dadA) 1/2 from dadBlue print of lifeBlue print of life
Q) What does DNA mean?Q) What does DNA mean?
A) Deoxyribonucleic AcidA) Deoxyribonucleic Acid
Q) Where does DNA come
Q) Where does DNA comefrom?from?
A) 1/2 from momA) 1/2 from mom
A) 1/2 from dadA) 1/2 from dadBlue print of lifeBlue print of life
DNADNADNADNA
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Maternal
Chromosome
Maternal
Chromosome
Paternal
Chromosome
Paternal
Chromosome
Where does DNA come from?Where does DNA come from?
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Cell TypesCell Types
BloodBlood
SweatSweat
Hair RootsHair RootsSalivaSaliva
Vaginal SecretionVaginal SecretionSemenSemen
SAME
Various TissueVarious Tissue
Where can DNA be found?Where can DNA be found?
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How does DNA help us?
Practical application of DNA
Fingerprinting
In cases of sexual offences
In case of unsuspicious deaths
Dispute of paternity / maternity Criminal identification
Personal identification
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What is DNA finger printing
It is a technique of decoding of geneticinformation for the furtherance of justice.
The chemical structure of everyones DNA issame
The only difference is in the sequence ofbase pairs
Every person has different sequence ofbase pair
This unique pattern give every individualspecific fingerprint (DNA fingerprint
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How is DNA fingerprinting done?
Scientist use a small no of DNA
secquences that are known to
vary among individuals a great
deal, and analyze those to get a
certain probability of a match.
Steps:-
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TECHNIQUES
RFLP
PCR
STR
mDNA
Y-Chromosomal DNA
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Step 1:-
Isolation of DNA from rest of the cellular material
Step 2:-
Denaturing the DNA, either by heating of or
chemically treating DNA in to gel, so that allthe DNA is rendered single-stranded.
Step 3:-
Blotting the DNA, this allows to identify, in aparticular persons DNA the occurrence and frequency
of the particular genetic pattern.
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The pure DNAis suspended in
a liquid
The pure DNAis suspended in
a liquid
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- Blood
- Hair Roots
- Saliva- Sweat
- Semen
- Various Tissue
- Blood
- Hair Roots
- Saliva- Sweat
- Semen
- Various Tissue
Chemical
DNADNA
Isolation ofDNAIsolation ofDNA
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Genetic Material
DNA
Genetic Material
DNA
Cellular WasteCellular Waste
Extraction of DNA from
rest of the cellular waste
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Blotting the DNA
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EXTRACTION
QUANTITATION
PCR CHECKING OF AMPLIFIED PRODUCT
PAGE (poly acrylamide gel electrophoresis)
DOCUMENTATION SEQUENCING
STEPS
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Step 2:-
Creating a hybridization reaction
Binding occurs b/w base pairs
A-T two H-bonds
C-G three H-bonds
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Denaturing the DNA:- Radioactive probe is allowed to bind with the
single strand DNA
Only the area bind with the probe will be
shown up on the film.
Radioactive Probe
Radioactive Probe
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G
T
A
G
A
A T
C
A
T
C
T
Heat
Step one of a single cycleStep one of a single cycle
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T
Step two of a single cycleStep two of a single cycle
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Step three of a single cycleStep three of a single cycle
T
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Every strand of DNA has pieces
that contain genetic information
(exons)And
Pieces that contain no geneticinformation are Introns.
Introns contain repeated
sequence of base pairs calledVNTRs
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Short Tandem Repeats
AGAT AGAT AGAT AGAT
Short Tandem Repeats
AGAT AGAT AGAT AGAT
AGAT AGAT AGAT AGAT AGAT AGAT AGAT 7
AGAT AGAT AGAT AGAT AGAT 5
(Core sequence AGAT)
STRSTR
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VNTRs
(Variable Number Tendem Repeat)
To determine if a person has a
particular VNTR, the above
process is applied and DNAsequence is amplified and then
studied.
Example:-
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1 Cycle2 Cycles
3 Cycles
4 Cycles
5 Cycles
30 Cycles
AmplificationAmplification
DNA
PCR (Polymerase Chain Reaction)PCR (Polymerase Chain Reaction)
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Amplified
DNA
Amplified
DNA
DNA
Profile
DNA
Profile
Analysis of amplified DNAAnalysis of amplified DNA
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DNADNA
SolutionSolution
(making copies)(making copies)
AmplificationAmplification
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A given person VNTR come from geneticinformation donated by his parents.
It is not possible to have VNTR other than his
parents. So Mrs John (blue) and Mr John (yellow) and their
four clildren D1 Mrs John (blue) daughter
D2 Mr John (yellow) step daughter (red) S1 Mr & Mrs John
S2 Mr & Mrs adopted son (light and & dark green)
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Mr & Mrs John and their children genetic information
Mrs John (blue)
Mr John (yellow)
D1 daughter of Mr& Mrs John (blue &yellow)
D2 Mr John(yellow) stepdaughter (red)
S1 Mr & Mrs John
S2 Mr & Mrsadopted son (lightand & dark green)
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