1. Molecular Genetics Structure of DNA

2. Phoebus Levene (1920’s) identified the 3 components of DNA molecule –deoxyribose sugars –phosphate groups –nitrogenous bases 4 nitrogenous bases identified by 1949

3. Erwin Chargaff (1949) isolated DNA from different organisms and measured levels of each of the 4 nitrogenous bases amt. of adenine = amt. of thymine amt. of cytosine = amt. of guanine

4. Rosalind Franklin produced X-ray diffraction images of DNA that suggested its double helix shape diameter 2nm, one turn 3.4nm See animation: http://www.dnalc.org/view/15014- Franklin-s-X-ray-diffraction- explanation-of-X-ray-pattern-.html http://www.dnalc.org/view/15014- Franklin-s-X-ray-diffraction- explanation-of-X-ray-pattern-.html

5. James Watson & Francis Crick (1952) used information from Chargaff and Franklin’s work proposed a model of DNA with a double helix of 2 anti-parallel strands won the Nobel Prize in 1962 (with Maurice Wilkins) for deducing the structure of DNA http://www.dnaftb.org/dnaftb/19/concept/index.html

7. Structure of DNA Review of 1.5 p.45-46

8. Nucleic Acids polymers of nucleotides: 5 carbon sugar (ribose or deoxy-) nitrogenous base C 1 phosphate group C 5

9. RNA vs DNA

11. DNA & RNA Directionality