1. Molecular Genetics History of DNA

2. Discovery of DNA Friedrich Miescher (late 1860s) - collected used bandages at hospitals and immersed in salt solution (to release cells) -alkaline solution caused lysis of cells and nuclei to precipitate out -isolated substance with high P content in the nuclei, called it “nuclein” -http://www.dnaftb.org/dnaftb/15/concept/http://www.dnaftb.org/dnaftb/15/concept/

3. Frederick Griffiths (1920s) (Image from: http://www.thefullwiki.org/Griffiths_experiment)

4. Joachim Hämmerling (1930s) (Image from: http://www.seavegetables.com/handbook/genera/greens/Acetabularia/Acetabularia.htm) experiments with single-celled alga called Acetabularia determined that the nucleus is the organelle that contains hereditary information

5. Hämmerling Expts (1930s) (Image from: http://www.accessexcellence.org/RC/VL/GG/hammerling_s.php)

6. Hämmerling Expts (1930s) (Image from: http://www.biologie.uni-hamburg.de/b-online/e14/9.htm)

7. DNA or protein? (Image from: http://textbookofbacteriology.net/phage.html) Alfred Hershey & Martha Chase (1952) experiments with virus: bacteriophage T2 bacteriophage infects bacteria cells by attaching itself and injecting its DNA into the cell

8. DNA or protein? Bacteriophage cells infecting bacteria cells:

9. DNA or protein? Alfred Hershey & Martha Chase (1952) - proteins contain sulfur but not phosphorus - DNA contains phosphorus but not sulfur - Hershey & Chase tagged viral proteins with radioisotope 35 S and viral DNA with radioisotope 32 P - after infection by labelled bacteriophages, bacteria cells were isolated from protein coats of viruses

10. DNA or protein? Alfred Hershey & Martha Chase (1952) - bacteria cells contained 32 P but no 35 S - culture medium (containing viral protein coats) contained 35 S

11. DNA or protein? http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter14/animations.html

12. Molecular Genetics Structure of DNA

13. Composition of DNA Erwin Chargaff (1949) - isolated DNA from different organisms and measured levels of each of the 4 nitrogenous bases - amts of adenine = amts of thymine - amts of cytosine = amounts of guanine

14. Rosalind Franklin (1953) (Image from: http://www.stanford.edu/group/ccr/blog/2009/04/a_closer_look_1.html) produced X-ray diffraction images of DNA that suggested its double helix shape 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

15. Structure of DNA James Watson & Francis Crick (1953) -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 for deducing the structure of DNA http://www.dnaftb.org/dnaftb/19/concept/index.html

16. Structure of DNA James Watson & Francis Crick (1953)

17. Structure of DNA 4.2 See also 1.2 (pages 52-54)

18. Nucleic Acids (Image from: http://giangleblog.wordpress.com/2011/05/02/edit-5-dna-structure-group-b/) polymers of nucleotides: 5 carbon sugar (ribose or deoxy-) nitrogenous base C 1 phosphate group C 5

19. RNA vs DNA (Image from: http://www.biology.lsu.edu/introbio/summer/Summer2004/1201/RF/Chapter%205%20review.htm)

20. RNA vs DNA (Image from: http://dedunn.edublogs.org/2011/06/08/structure-of-dna-and-rna/)

21. DNA & RNA Directionality (Image from: http://www.phschool.com/science/biology_place/biocoach/transcription/chains.html)