1

•DNA stands for deoxyribose nucleic acid

It’s a macromolecule found in the nucleusof all cells 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

What is DNA? 2

•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)

What is a DNA molecule?3

The four bases are:

Adenine (A)

Thymine (T)

Cytosine (C)

Guanine (G)

What are the 4 bases? 5

The deoxyribose,

adenine

Deoxyribose (sugar)

PO4

the phosphate and one of the 4 bases

combine to form a nucleotide:

What forms a nucleotide?6

(base)

PO4

PO4

PO4

PO4

•A molecule of human DNA is formed by billions of nucleotides joined together in a long chain

sugar-phosphate backbone

+ bases

How do nucleotides form a strand of DNA?

7

•In fact, the DNA consists of a double strand of nucleotides

PO4

PO4

PO4

PO4

PO4

PO4

PO4

PO4

PO4

PO4

PO4

PO4

PO4

PO4

PO4

PO4

2-stranded DNA 9

The bases always pair up in the same way

Adenine forms a bond with Thymine

and Cytosine bonds with Guanine

How do bases pair together?10

Adenine Thymine

Cytosine Guanine

PO4

PO4

PO4

thymine

PO4

PO4

PO4

PO4

adenine

cytosine

PO4

guanine

Bonding 2 11

The paired strands are coiled into a spiral called

A DOUBLE HELIX(or TWISTED LADDER)

13

What is the structure of DNA called?

•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!

Cool Facts!!!!!