3. Deoxyribonucleic Acid Primarily in nucleus Contains the code for making proteins Can’t get out of the nucleus Very large molecule Made of nucleotides

4. Nucleotides Each nucleotide consists of -one sugar (deoxyribose) -One phosphate -One nitrogen base

5. Nitrogen Bases Adenine Thymine Guanine Cytosine

6. Hydrogen Bonds Adenine and Thymine have 2 Guanine and Cytosine have 3 DALLEN: A = T C = G

7. Nucleotides Connected 4 nucleotides are attached here

8. The Double Helix

9. How does DNA fit into a cell?

10. Discoverers of DNA Structure James Watson and Francis Crick Co-discoverers: Rosalind Franklin and M.H.F. Wilkins Nobel Prize in 1953 (except Franklin, who had died)

11. DNA Replicates Replication – makes a copy of itself Occurs just before cell division Necessary so that each new cell gets a copy of the parent cell’s DNA Occurs in nucleus during interphase

14. Replication Steps H-bonds between N-bases break. This causes the molecule to unzip. Unattached N-bases attract their complementary base. Adenine – Thymine (T-A or A-T) Cytosine – Guanine (G-C or C-G) New strands are formed – each has the same number and order of bases.

15. DNA Replication in Action

16. New DNA Strands are Identical

17. DNA is now copied so mitosis or meiosis can take place.

18. The End