it is a little powerpoint presentation by me about DNA DEnaturation wish you all benefit from it . for any , contact me at iahmedaly55@gmail.com

1. Biochemistry Department.
Course Code :701
Instructor : Dr/Omneya
DNA Denaturation

2. Outlines :-
A. Introduction.
B. What's meant by DNA Denaturation.
C. Causes of DNA Denaturation.
D. Characters of Denatured DNA .
E. Diseases caused by DNA Denaturation.
F. DNA renaturation.
G. Application on DNA denaturation and renaturation.
H. References.
I. Participants.

3. A. Introduction
-DNA is a double helix
composed of 2 strands
running in opposite
directions .
-Each strand composed of
backbone of deoxy-ribose
“sugar molecules linked
together by phosphate
linkage” .

4. •Each sugar molecule covalently
linked to one of four bases
Adenine, Guanine, Cytosine
and Thymine.
•The two strands connected
together by H-bond.

5. A.2. Function of DNA.
1. Stores an organism genetic material in the nuclei.
2. Replicates itself when dividing.
3. Provide code or template for particular
sequencing of amino acid that bond together and
make protein.

6. B.“DNA Denaturation” Definition
DNA Denaturation is the
separation of a double strand into
two single strands, which occurs
when the hydrogen bonds
between the strands are broken.

7. C.Causes of Denaturation.
Denaturation can occur when proteins
and nucleic acids are subjected to :
1-elevated temperature.
2-extremes of pH.
3-nonphysiological concentrations of
salt, organic solvents, urea, or other
chemical agents.

8. C.1-elevated temperature.
The most common
type of denaturation is
thermal denatuation.
Tm : temp at which
DNA is half denatured.
*above Tm DNA is
single strands.
*below tm DNA is
double strands.

9. C.2-extremes of pH
At high PH the hydroxide
ions (( negatively charged
ions )) can pull hydrogen
ions from base pairs –
forming H bond between
two strands – causing
them to separate.

10. C.3 non physiological salts
Low salt concentration could also denature
DNA double-strands by removing ions that
stabilize the negative charges on the two
strands from each other.

11. D. Characters of Denatured DNA
1. Hyperchromic : increase the absorbance (A260)
upon denaturation.
2. The rate of increase in absorbance is directly
proportional to the rate of denaturation.
3. Viscosity decrease upon denaturation.

12. E.Diseases caused by DNA denaturation
DNA repair deficiency disorder is a medical condition due to
reduce functionality of DNA repair .
DNA repair defects can cause both an accelerated aging
disease and an increase risk of cancer.
Examples for DNA defects accelerated aging :
1.Bloom syndrome.
2.Fanconi`s anemia.
3.Xeroderma pigmentosum.

13. DNA repair defects and increased cancer risk :
When a mutation is present in a DNA repair
gene, the repair gene will either not be
expressed or expressed in an altered form so
the repair function will likely be deficient .
DNA synthesis leading to mutations , some of
which may give rise to cancer .

14. F.DNA Renaturation
Renaturation or annealing :
I. is the formation of base repairs and complementary strands
of DNA come back together.
II. Renaturation occurs if double stranded DNA is heated
above tm then the temperature is slowly decreased under
appropriate conditions.

15. F.Applications on DNA denaturation and renaturation
1. Understanding the genome size and
complexity.
1. Understanding genetic relatedness.
2. Understanding relative proportion of
single copy and repetitive sequences.

16. G.References
1. Lecture notes “illustrated
biochemistry I “ .
2. Harper`s illustrated Biochemistry.
3. Lippincott's illustrated reviews.
4. Oraby`s illustrated reviews of
biochemistry.