1. Interest Grabber Order! Order!
Section 12-1
Order! Order!
Genes are made of DNA, a large, complex molecule. DNA is composed of individual units called nucleotides. Three of these units form a code. The order, or sequence, of a code and the type of code determine the meaning of the message.
1. On a sheet of paper, write the word cats. List the letters or units that make up the word cats.
2. Try rearranging the units to form other words. Remember that each new word can have only three units. Write each word on your paper, and then add a definition for each word.
3. Did any of the codes you formed have the same meaning?
4. How do you think changing the order of the nucleotides in the DNA codon changes the codon’s message?
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2. Search for DNA Three major experiments
Conclusion- DNA is genetic material in cells

3. Figure 12–2 Griffith’s Experiment
Section 12-1
Heat-killed, disease-causing bacteria (smooth colonies)
Harmless bacteria (rough colonies)
Control (no growth)
Harmless bacteria (rough colonies)
Heat-killed, disease-causing bacteria (smooth colonies)
Disease-causing bacteria (smooth colonies)
Dies of pneumonia
Dies of pneumonia
Lives
Lives
Live, disease-causing bacteria (smooth colonies)
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4. Conclusion Genetic material could be transferred between cells
What is that material????

5. Avery’s Experiment Was transforming material protein, RNA, or DNA???
Used enzymes to destroy each material in heat killed S bacteria

6. Conclusion
Bacteria missing protein or RNA would transform R cells into S cells.
Bacteria missing DNA did NOT transform R cells.
DNA is responsible for transformations

7. Hershey-Chase Support Avery’s conclusions
Show how DNA and proteins cross cell membranes

8. Figure 12–4 Hershey-Chase Experiment
Section 12-1
Bacteriophage with phosphorus-32 in DNA
Phage infects bacterium
Radioactivity inside bacterium
Bacteriophage with sulfur-35 in protein coat
Phage infects bacterium
No radioactivity inside bacterium
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9. Conclusion
Only DNA of viruses enter bacterial cells

10. Figure 12–7 Structure of DNA
Section 12-1
Nucleotide
Hydrogen bonds
Sugar-phosphate backbone
Key
Adenine (A)
Thymine (T)
Cytosine (C)
Guanine (G)
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11. DNA Deoxyribonucleic acid Double helix (winding staircase)
Monomers: nucleotides

12. Figure 12–5 DNA Nucleotides
Section 12-1
Purines
Pyrimidines
Adenine
Guanine
Cytosine
Thymine
Phosphate group
Deoxyribose
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13. DNA Structure Chargaff- A = T and G = C
(Info used to determine base pairing)
Franklin & Wilkens- x-ray diffraction images showed tightly coiled helix of 2 or 3 chains of nucleotides
**Watson & Crick-
(Info used to create 3-D image of DNA)