DNA

The CodeAll cells use a code that is stored in its

hereditary material…the code is DNA.

DNA is a chemical called deoxyribonucleic acid.

DNA contains information for an organism’s growth and function.

Every cell that has ever been formed in your body or in any other organism contains DNA.

Who discovered it?Mid 1800s: Scientists have known that

the nuclei of cells contain large molecules called nucleic acids.

1950: Chemists had learned what DNA was made of, but they didn’t understand the parts and how they were arranged.

DNA Structure1953: Rosalind Franklin discovered that

DNA is two chains of molecules in a spiral form. How did she discover this?

Ultimately she discovered that the structure of DNA is similar to a twisted ladder.

1953: Using the work of Franklin, James Watson and Francis Crick made a model of DNA molecule.

DNA ModelEach side of the “ladder” is made up of

sugar-phosphate molecules.

Each molecule consists of the sugar called deoxyribose and a phosphate group.

The rungs of the “ladder” are made up of other molecules called nitrogen bases. Four kinds of nitrogen bases are found in DNA:Adenine (A)Guanine (G)Cytosine (C)Thymine (T)

How does it work?The amount of cytosine always equals the

amount of guanine. C=G

The amount of adenine always equals the amount of thymine. A=T

This led to the hypothesis that they always occur in pairs. Each base bonds only with its correct partner.