1. What are all living things made up of?
Brain Pop
What are all living things made up of?

2. 1
DNA
The illustration is a ‘model’ of the double helix forming part of a DNA molecule
(Slide 14)

3. DNA DNA stands for deoxyribose nucleic acid2
DNA stands for deoxyribose nucleic acid
This chemical substance is present in the
nucleus of all cells in all living organisms
DNA controls all the chemical changes
which take place in cell.
***The kind of organism which is produced
(butter-cup,giraffe, herring, human etc.) is
controlled by DNA

4. DNA molecule DNA is a very large molecule made up of a3
DNA is a very large molecule made up of a
long chain of sub-units
The sub-units are called nucleotides
Each nucleotide is made up of :
a sugar called deoxyribose
2. a phosphate group -PO4 and
3. an organic nitrogen base

5. Both molecules may be represented by the4
Deoxyribose is almost the same but lacks
one oxygen atom
Both molecules may be represented by the
symbol

6. The bases The most common organic bases are Adenine (A) Thymine (T)5
The most common organic bases are
Adenine
(Purines)
(A)
Thymine
(Pyrimidines)
(T)
Cytosine
(Pyrimidines)
(C)
Guanine
(Purines)
(G)

7. Nucleotides The deoxyribose, the phosphate and one of the bases6
The deoxyribose,
the phosphate
and one of the bases
Combine to form a nucleotide
adenine
deoxyribose
PO4
It is the phosphate group which gives DNA its acidic properties

8. Joined nucleotides 7
PO4
sugar-phosphate
backbone
+ bases
A molecule of DNA is formed by millions of nucleotides joined together in a long chain

9. In fact, the DNA usually consists of a double strand of nucleotides8
In fact, the DNA usually consists of a
double strand of nucleotides
The sugar-phosphate chains are on the
outside and the strands are held together by
chemical bonds between the bases

10. 2-stranded DNA 9 Sugar Phosphate bonds Chemical Bonds PO4 PO4 PO4 PO4

11. 14
THE DOUBLE HELIX
bases
sugar-phosphate
chain

12. Bonding 1 The bases ALWAYS pair up in the same way10
The bases ALWAYS pair up in the same way
Adenine (A) forms a bond with Thymine (T)
Adenine
Thymine
and Cytosine (C ) bonds with Guanine (G)
Cytosine
Guanine

13. 11
Bonding 2
PO4
adenine
cytosine
PO4
thymine
PO4
guanine
PO4
PO4

14. 13
The paired strands
are coiled into
a spiral called
A DOUBLE HELIX