1. DNA Structure Deoxyribonucleic Acid pp. 193-199

2. Location  Prokaryotes: floats in cytoplasm  Eukaryotes: wrapped around proteins in the nucleus

3. DNA  Stores and transmits genetic information to make proteins  Made up of repeating units of nucleotides

4. DNA  Nucleotides have three parts:  Deoxyribose Sugar  Phosphate Group  Base

5. DNA Bases  Purines : Two- ringed bases  Adenine and Guanine  Pyrimidines : One- ringed Bases  Thymine and Cytosine

6. Complementary Base Pairing  Purine bonds to Pyrimidine  Adenine bonds to Thymine  Guanine bonds to Cytosine

7. DNA Bonds  Bases are held together by weak hydrogen bonds.  The DNA Backbone is held together by covalent bonds between the phosphate group and the deoxyribose sugars.

8. DNA Structure  DNA is double- stranded and coiled like a spiral staircase.  Backbone is like the railing and the bases are the steps.  This shape is called a double helix.

10. Vocabulary  Double Helix  Adenine  Guanine  Thymine  Cytosine  Turn to the person next to you and discuss: - Which are Purines? - Which are Pyrimidines? - Which help determine DNA structure?