1. The Structure of DNA

2. DNADNA The blueprint of life (instructions for all living things). D= “deoxyribose” N= “nucleic” A= “acid” DNA = Deoxyribonucleic acid!

3. DNA: The Genetic Material Genes are segments of DNA that code for a specific inherited trait. DNA is the primary material that causes recognizable, inheritable characteristics in related groups of organisms.

5. Genome A genome is a complete set of genetic information for an organism. It contains all the genes needed to make more of that organism.

6. Human Genome Project Took over 12 years Powerful tools to study the role that multiple genetic factors acting together and with the environment play in much more complex diseases Diseases, such as cancer, diabetes, and cardiovascular disease constitute the majority of health problems in the United States

7. Searching for the Genetic Material In the 1800s Gregor Mendel showed that traits are passed from parents to offspring (cross- bred pea plants to see what traits were passed on).

8. Mendel didn’t know HOW traits were passed on. Many years later, 3 major experiments lead to the conclusion that DNA is the genetic material in cells.

9. The Race Is On! In the 1950s, we knew genes were made of DNA but knew nothing about its structure. Scientists around the world were actively searching for more information about DNA

10. James Watson & Francis Crick Created the “double helix” model that is composed of 2 nucleotide chains. The chains are twisted around a central axis and are held together by hydrogen bonds.

11. Double Helix Model (Spiral Staircase)

12. Nucleotide Subunits (Review – 3 parts)

13. The 4 Nitrogen Bases of DNA: The bases of the nucleotides pair together to connect the 2 strands.

14. The Information in DNA The structure of DNA is very important in the transfer of genetic information because the order of the bases creates a code.

15. Nitrogenous Bases Purines – Have 2 rings of carbon & nitrogen atoms per base. A – adenine G – guanine Pyrimidines – Have 1 ring of C & N atom per base T – thymine C – cytosine

16. How did Watson & Crick determine this 3-D structure? 1. In 1949, Erwin Chargoff found that there was always the same amount of adenine as thymine and the same amount of cytosine as guanine.

17. Chargoff’s (Base- Pairing) Rule A purine on one strand of DNA is always paired with a pyrimidine on the other A always with T G always with C These are called “complementary base pairs.” T T

18. 2. In 1952, Rosalind Franklin & Maurice Wilkins developed high quality x-ray images of strands of DNA. Images resembled a tightly coiled helix of 2 chains.

19. In 1953, Watson & Crick used the findings of Chargaff & Franklin to create a 3-D model of DNA. Nobel Prize for their discovery in 1962.