DNA STRUCTURE AND TYPES

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2. INTRODUCTION OF DNA
• DNA is a double stranded molecule that is
twisted into a Helix
• DNA are macromolecular structures
composed of regular repeating polymers
formed from nucleotides.
• DNA is a complex molecule that contains of
the information necessary to build and
organism

3. COMPONENTS
OF NUCLOTIDE
Nitrogenous Bases
Deoxyribose Sugar
Phosphate Group
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4. NITROGENOUS
BASE
CYTOSINE
THYMINE
ADENINE GUANINE
• CYTOSINE
• THYMINE
PYRIMIDINE
• ADENINE
• GUANINE
PURINE
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5. DEOXYRIBOSE
SUGAR
• The sugars found in
nucleic acids are pentose
sugar ; a pentose sugar
has five carbon atoms.
• Deoxyribose, found in
DNA , is a modified
sugar , lacking one
oxygen atom (hence the
name “deoxy”).
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6. PHOSPHATE
GROUP
• A phosphate group is
just a phosphorus atom
bound to four oxygen
atoms , but it has many
important roles.Along
with sugars and bases, it
makes up nucleic acids.
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7. THE SECONDARY
STRUCTURE OF DNA
• The sides of the ladder are made up of
alternating molecules of phosphate
and deoxyribose.
• The bases make up the rungs of the
ladder are attracted by a weak
chemical bonds called hydrogen
bonds.
Watson and Crick Model
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8. A-DNA
• A-DNA is one of the many possible double helical structures of
DNA.
• It is most active along with other forms.
• Shorter more compact helical structure.
• Such as those used in crystallographic experiments.
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9. B-DNA
• Helical sense : right handed.
• Base pairs : almost perpendicular to the ,helix axis ; 3.4
angstrom apart.
• One turn of the helix : 36 angstrom; which is equals to 10.4
base pairs. 9

10. Z-DNA
• Z-DNA is one of the many possible double helical structures of DNA.
• Helix has left-handed sense.
• It is most active double helical structure.
• Z-DNA was first discovered in 1979,certain proteins bind very strongly to
Z-DNA.
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