1. Structure of DNA Notes 12/17

2. The Double Helix Made up of units called nucleotides, which have three parts

3. The Double Helix Made up of units called nucleotides, which have three parts –Deoxyribose (5-carbon sugar)

4. The Double Helix Made up of units called nucleotides, which have three parts –Deoxyribose (5-carbon sugar) –Phosphate group

5. The Double Helix Made up of units called nucleotides, which have three parts –Deoxyribose (5-carbon sugar) –Phosphate group –Nitrogeous base (contains nitrogen)

6. The Double Helix Nucleotides are paired together and form very long chains called DNA molecules Called the double helix because of the way the two strands wind around each other

7. There are FOUR types of nucleotides; they differ in the nitrogeous base present: –Adenine and guanine (purines) –Cytosine and thymine (pyrimidines)

9. Base Pairing Because a DNA molecule has two strands, these four bases pair together.

10. Base Pairing Because a DNA molecule has two strands, these four bases pair together. Adenine (A) always pairs with Thymine (T) Guanine (G) always pairs with Cytosine (C)

11. Length A human DNA molecule is over 1 meter (more than three feet) in length! We have 46 of these in most cells in our body How do they fit? –Tightly packaged to form chromatin (DNA molecule wrapped around proteins called histones)

12. DNA Text Assignment Read p. 291-296 –In your journal, complete the following: p. 294: #2-4 Define: nucleotides, base pairing, chromatin, histones