DNA is a macromolecule found in all living organisms that controls the type of cell and organism formed. It is a long chain of nucleotides, where each nucleotide contains a sugar, phosphate group, and one of four bases (A, T, C, G). The bases bond together in a specific pairing - A pairs with T and C pairs with G. Billions of these bonded nucleotides join together to form the iconic double helix structure of DNA.

1. 1

2. What is DNA? 2
•DNA stands for deoxyribose nucleic acid
•It’s a macromolecule found in all living organisms
•The kind of cell which is formed, (muscle, blood,
nerve, etc) is controlled by DNA
•The kind of organism which is produced (dog,
giraffe, frog, human, etc) is controlled by DNA

3. 3
What is a DNA molecule?
•DNA is a very large molecule made up of a long
chain of sub-units
•The sub-units, or monomers, are called nucleotides
•Each nucleotide is made up of:
-a sugar called deoxyribose
-a phosphate group -PO4 and
-A base (Adenine, Guanine, Cytosine or Thymine)

4. What are the 4 bases? 5
The four bases are:
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)

5. 6
What forms a nucleotide?
The deoxyribose, the phosphate and one of the 4 bases
combine to form a nucleotide:
PO4
adenine
(base)
Deoxyribose (sugar)

6. How do nucleotides form a strand of 7
DNA?
PO4
•A molecule of human
DNA is formed by
PO4 billions of nucleotides
joined together in a
long chain
PO4
PO4
•In fact, the DNA consists
of a double strand of
nucleotides
sugar-phosphate + bases
backbone

7. 2-stranded DNA 9
PO4
PO4
PO4
PO4
PO4 PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4
PO4

8. 10
How do bases pair together?
The bases always pair up in the same way. They
are joined by a hydrogen bond.
Adenine forms a bond with Thymine
Adenine Thymine
and Cytosine bonds with Guanine
Cytosine Guanine

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

10. 13
What is the structure of DNA called?
The paired strands are coiled into a spiral called
A DOUBLE HELIX
(or TWISTED LADDER)

11. Cool Facts!!!!!
•The DNA of humans is
composed of
approximately 3 billion base
pairs.
•If you stretched out the DNA
in every cell,
it would be almost a meter long!