2. DNA was first isolated by the Swiss physician Friedrich Miescher who, in 1869, discovered a microscopic substance in the pus of discarded surgical bandages In 1953, based on X-ray diffraction images taken by Rosalind Franklin and the information that the bases were paired, James D. Watson and Francis Crick suggested what is now accepted as the first accurate model of DNA structure.

3. Franklin's work was used without her knowledge. She was not congratulated for her important discovery, was not invited to work together over the DNA structure model. There have been assertions that Rosalind Franklin was discriminated against because of her gender. 'Rosy' was dismissed in James Watson's account of the discovery

4. Deoxyribonucleic acid is a nucleic acid that contains the genetic instructions used in the development and functioning of all known living organisms and some viruses DNA is often compared to a set of blueprints, since it contains the instructions needed to construct other components of cells

5. Within cells, DNA is organized into structures called The DNA segments that carry this genetic information are called genes The main role of DNA molecules is the long-term storage of information Chromosomes

6. The shape of the DNA molecule is a double-helix (like a twisted ladder). The sides of the ladder are composed of alternating sugars (deoxyrib ose ) and phosphates. The rungs (steps)of the ladder are composed of nucleotides.

7. Adenine pairs to Thymine Guanine pairs to Cytosine Four Types of Nucleotides (also called Bases) Adenine Thymine Guanine Cytosine Nucleotides pair in a specific way – called the Base-Pair Rule

8. The rungs of the ladder can occur in any order (as long as the base-pair rule is followed)

9. It is the sequence of these four bases along the backbone that encodes information