DNADeoxyribonucleic Acid

DNA Structure

What is DNA?

The information that determines an organism’s traits.

Stores and passes on genetic information from one generation to the next.

DNA produces proteins which gives it “The power”

Many things contain and are made of proteins.

Skin, hair, bones, etc are made of proteins.

What is DNA? Cont’d

Enzymes are special proteins. Enzymes control chemical reactions

needed for life. DNA contains all the information for

making all and any proteins for human life.

DNA Structure:

DNA is made of repeating subunits called nucleotides.

Nucleotides have three parts:– Simple sugar– Phosphate group– Nitrogen base

1 Nucleotide

Phosphate Group

Sugar (Deoxyribose)

Nitrogen Base

DNA Structure The simple sugar is called deoxyribose.

The phosphate group is made of phosphate and oxygen.

DNA Structure

Four possible Nitrogen Bases:– Thymine (T)– Adenine (A)– Cytosine (C)– Guanine (G)

DNA

Nucleotides join together to form long chains.

The phosphate group of one nucleotide joins together with the deoxyribose sugar of an adjacent nucleotide.

“Backbone”

“Teeth”

DNA

Nitrogen bases pair up

– Adenine & Thymine (A-T)

– Cytosine & Guanine (C-G)

Complementary bases

Watson & Crick and Franklin, Watson & Crick and Franklin, 19531953

Rosalind Franklin is the first one to see the DNA

Watson and Crick Proposed DNA is put together like a “twisted zipper”

DNA = 2 chains of nucleotides joined by nitrogen bases

Watson & Crick, 1953Watson & Crick, 1953Double HelixDouble Helix

Double = DNA has two strands

Helix = twisted like a spring, “spiral”

Importance of Sequencing The sequence of the four different nucleotides

determines what organism is created.

For instance: T-A-A-G-C-A is different than A-T-C-A-A-G

Another example: E-A-R-T-H is different than H-E-A-R-T

vs.

Importance of Sequencing

The more similar the order of nucleotides are, the closer the relationship between 2 organisms

1 Nucleotide

Phosphate Group

Sugar (Deoxyribose)

Nitrogen Base