DNA contains genetic instructions that are passed down from parents to offspring. It is located in the nucleus of cells and takes the form of a double helix structure. Genes within DNA control hereditary traits by producing proteins. Mutations, or changes in genes, can result in new traits being expressed. DNA replication and cell division allow genetic material to be inherited from generation to generation.

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3. Cellular composition
DNA is contained in nucleus of cell

4. Where is DNA located in the Cell?

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9. Genes
What are the genes?
They are parts of DNA present on
the chromosomes and control the
individual hereditary traits

10. •Every living thing has DNA. That means that you
have something in common with a zebra, a tree, a
mushroom and a beetle!!!!.
•Dna is like a fingerprint because everyone’s is a
little different!
•It contains information equal to some 600,000
printed pages of 500 words each!!!
(a library of about 1,000 books)

11. • Discovery of the DNA double helix
A. Frederick Griffith – Discovers that a factor in
diseased bacteria can transform harmless bacteria
into deadly bacteria (1928)
B. Rosalind Franklin - X-ray photo of DNA.
(1952)
C. Watson and Crick - described the
DNA molecule from Franklin’s X-ray.
(1953)

12. composition of DNA
• DNA molecule is composed of two stands
coiled around each other like the spiral ladder
called the double helix
• The sides of ladder consisted of :
-sugar molecules
-phosphate groups

13. DNA (DeoxyriboNucleic Acid)
• Backbone is made of
sugar-phosphate
• Base pairs bind the
backbone together

14. DNA molecule
1-the gene is the building block of nucleic acid (DNA)
2-the gene consists of more smaller blocks called
Nucleotides
each nucleotide consists of three components :
1- phosphate group
2-deoxyribose sugar
3-nitrogenous base (4 types)

15. •In 1953 Watson and
Crick determined the
structure of DNA:-
•DNA and its Building
Nucleotides:
Guanine (G)
Adenine (A)
Cytosine (C)
Thymine (T).
•Base inside, sugar
outside

16. There are four types of nitrogenous base
1-Adenine A )
2-Thymine T)
3-cytosine C)
4-guanine G)
• Adenine always
pairs with Thymine
• Guanine binds with
Cytosine
DNA forms double helix with two complimentary strands
holding together by hydrogen bonds
between A-T (2 bonds) and G-C (3 bonds)

18. A T
C
G
T A
C
G
A T
G C
T A

19. Function of DNA
• Genetic information is carried in the
linear sequence of nucleotides in
DNA
• Genetic information contains
instructions to synthesize proteins

20. How do you inherit your genes ?
1-By MEIOSIS DIVISION reproductive cells produce:
o Male gametes(sperms) containing half number of
chromosomes(N)
o Female gametes(ova) containing half number of
chromosomes (N)
2-After fertilization, a zygote (contain 2N of
chromosomes )
3-The cell group together forming tissues which
form organs until all the body of the fetus is
formed

21. • How do the genes perform their function ?
Every
gene
Produce
A specific
enzyme
Responsible of occurrence of
Chemical forms A specific showing A special
hereditary
reaction protein
trait
They control body growth , features , function

22. DNA to Protein
Genome: the complete set of information in an organism’s DNA
Total length of DNA about 2 meters long in a human cell,
encoding about 30000 proteins

23. • Example :
• The inheritance of trait of eyes :
If you inherit one gene from one of your parents and
it is responsible for the brown coloured eyes trait
(the dominant trait )
• It is working on the formation of an enzyme which
is responsible for the occurrence of a chemical
reaction producing a protein that makes the trait of
the brown eye appears on you

24. Mutations
• What is meant by mutations ?
It is change in the natural of the hereditary
factors that control the traits of a living
organism which results in change in the living
organism traits
• How does the mutation occur?
Changing the chemical composition of one or
more genes leads to changing the hereditary
trait resulting from this gene . So a new trait
that never appeared in the parents

25. What Causes Mutations?
• There are two ways in which DNA can become
mutated:
– Mutations can be inherited.
• Parent to child
– Mutations can be acquired.
• Environmental damage
• Mistakes when DNA is copied

26. Results due mutations :
• The appearance of undesirable trait
like :
1)Birth deformation in the human and
the animal
2)Sterilization in plant
• The appearance of desirable changes
(rare)

27. Kinds of mutations
1-the site of occurrence :
• Genetic mutations
• Chromosomal mutations
2-The inheritance :
• Somatic mutations
• Gamete mutation
3-The origin :
• Spontaneous mutations
• Induced mutations

28. Genetic mutation
• What is meant by?
It is changing the chemical composition of one gene
or more
• How the genetic mutation occurs ?
The genetic mutation occurs when a change occurs in
the Nitrogenous bases of the gene
For example :
If (A)base is replaced with (C) base

30. Gene Mutations
• Point Mutations – changes in one
or a few nucleotides
– Substitution
• THE FAT CAT ATE THE RAT
• THE FAT HAT ATE THE RAT
– Insertion
• THE FAT CAT ATE THE RAT
• THE FAT CAT XLW ATE THE RAT
– Deletion
• THE FAT CAT ATE THE RAT
• THE FAT ATE THE RAT

31. • Example
The grey mice have MELANIN PIGMENT but the white
mice don't have this pigment due to a change in
the gene composition responsible for this trait

32. The origin of the mutation
1-The spontaneous mutation
2-The induced mutation
1-The spontaneous mutation
it is a mutation occurs due to the influence from the
surrounding environment
• It is occurs without the interference of the human
being
• Its percentage is very low

33. Reasons of its occurrence
• Radiation
• Chemical substance
• High or very low temperature
Its importance
It cause NATURAL VARIATION between the genera
and special of the animals and various plants ,
where the new traits that are produced from the
occurrence of mutations are inherited across the
successive generations

34. The induced mutation
• What is meant by ?
It is a mutation which is controller by human being to
obtain desirable traits
• Its important
It is obtain desirable traits in specific living organisms
especially in the plants

35. •