1. + January 7, 2015 Objectives: To understand how DNA was discovered To be able to model the structure of DNA Journal: Do you think that people have always known that DNA carries our genes? How do you think it may have been discovered? *** Hand in Race for DNA Structure Worksheet

2. + The Discovery of DNA Before the 1950s, scientists weren’t sure what genes were made of There was a race between the best scientists in the world to figure it out

3. + Experiments that Determined DNA was the Genetic Material in Cells Griffith’s Discovery of Transformation Discovered that genetic material could be transferred between cells Hershey-Chase Experiment Determined that DNA is the hereditary material instead of proteins Rosalind Franklin and Maurice Wilkins Took pictures of DNA using x-ray diffraction

4. + Experiments that Determined the Structure of DNA Chargaff Determined amount of A = T, C=G James Watson and Francis Crick Built model of DNA Credited with actually discovering DNA structure

5. Function of DNA  Contains the information on how to make proteins.  Proteins are the workers to put together and run a cell.

6. Nucleotide Structure – basic building block of DNA  Sugar  Phosphate Group  Nitrogen Base Sugar N. Base P Building blocks of DNA

7. + 1. Adenine 2. Guanine 4. Cytosine 3. Thyamine Four Different Nitrogen Bases

8. DNA Structure Double Stranded Helix

9. + Antiparallel Strands DNA strands run antiparallel, opposite of each other One runs from 5’ to 3’ the other runs from 3’ to 5’

10. Sides of the staircase = sugar & phosphates  Steps of the staircase = nitrogen bases. Spiral Staircase Structure

11. Base Pairing Rule: A – T held together by two hydrogen bonds C – G held together by three hydrogen bonds

12. Purines vs. Pyrimidines Purines Structure has two rings Adenine and Guanine Pyrimindines Structure has one ring Cytosine and Thymine

13. + The Race for DNA Structure Video https://www.youtube.com/watch?v=d7ET4bbkTm0