1. DNA
“THE BLUEPRINT OF LIFE”
SUJITA MISHRA
PI/289 1

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Contents
History of DNA
Genetic material of cells
DNA double helix
DNA replication
ABZs of DNA 2

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DNA
(Deoxyribonucleic Acid)
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A History Of DNA
 R.FRANKLIN X-ray photo of DNA.
 (1952)
 Watson & CrickDescribed the DNA from Franklin’s x-
ray.
 (1953)
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 GENESUnits of genetic material that codes for a
specific trait.
 DNA is made up of repeating molecules called as
Nucleotides.
Genetic Material Of Cells
What IS A NUCLEOTIDE ?
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DNA Nucleotide
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DNA Double Helix
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Nitrogenous Base
PURINES
• Adenine(A)
• Guanine(G)
PYRIMIDINES
• Thymine(T)
• Cytosine(C)
A or G
T or C
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DNA Replication
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THE ABZs OF DNA
Major forms Of DNA
A-DNA  Right handed,short & broad,11bp per turn.
B-DNA Right handed,longer,thinner,10 bp per turn.
Z-DNA Left handed,longest,thinnest,12 bp per turn.
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THE ABZs OF DNA
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 Observed in active site of DNA polymerase
 Gram+ bacteria undergoing sporulation.
 Deep major groove & shallow minor groove.
 Observed under dehydrating conditions.
 B-DNAA-DNA (Reversible).
A-DNA
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 Most common DNA.
 Each base pair has same width.
 Minor groove is narrow & major groove is wide.
B-DNA
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 Seen in conditions of high salt concentration.
 Deep minor groove.
 No discernible major groove.
Z-DNA
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