2. DNA Deoxyribonucleic Acid

3. Purpose DNA codes for proteins and is the blueprint for life. The same DNA is found in all cells in your body (sex cells have half of the DNA)! Only certain parts of the DNA molecule are read and used in each cell type.

4. DNA and Chromosomes Prokaryotes – DNA in circular form called “plasmid” –E. Coli has over 4.6 million base pairs! Eukaryotes –Linear DNA in form of chromosome –Human cells contain about 3 billion base pairs!

5. Chromosome Composition A Nucleosome is DNA tightly wound around protein spheres called “histones”

6. Nucleosomes supercoil and become thick fiber of chromosomes Nucleosomes play role in gene regulation – turning off and on genes

7. Structure Discovered by Watson and Crick in 1953 Shaped like a twisted ladder called a “double helix”

8. Rosalind Franklin Used X-Ray diffraction to get information about the structure of DNA:

9. Chargaff’s rules The relative amounts of adenine and thymine are the same in DNA The relative amounts of cytosine and guanine are the same.

11. Nucleotide Subunit of DNA made up of a sugar, phosphate and one nitrogen base.

12. What makes up the sides of DNA Ladder? 1.Deoxyribose sugar 2.Phosphate group

13. Run in opposite directions called “anti-parallel” Important when copying DNA Run in direction 5’-3’

14. Nitrogen bases make up Rungs PurinesPyrimidines (double ring)(single ring) Adenine-------( double H bond )--------Thymine Guanine-------( triple H bond )---------Cytosine

15. Putting it all together The order of bases in DNA makes you different from the person sitting next to you !