Chapter 12-1 Part 2.

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Presentation transcript:

Chapter 12-1 Part 2

II. Avery (1944) Wanted to determine what type of molecule was responsible for the transformation, the molecule that makes up genes. B. Repeated Griffith’s experiments C. Made an extract (solution) of heat killed smooth bacteria and rough bacteria

D. Added 5 different enzymes to the bacteria extract (enzymes that destroy different organic compounds) 1. Bacteria Extract + Protein destroying enzymes = transformation occurred (mouse alive or dead?) 2. Bacteria Extract + Lipid destroying enzymes = transformation occurred (mouse alive or dead?) 3. Bacteria Extract + Carb destroying enzymes = 4. Bacteria Extract + RNA destroying enzymes = 5. Bacteria Extract + DNA destroying enzymes = transformation DID NOT OCCUR (mouse alive or dead?)

E. Avery's Conclusion- DNA was the Transforming factor.

III. Hershey and Chase (1952) Wanted to know if genes were made of proteins or DNA? B. Used bacteriophages (phages)- a type of virus that attack bacteria. 1. Virus injects its genetic material into bacteria cell. 2. The cell now is a virus factory, making viruses according to the new viral DNA. 3. Cell Membrane bursts, killing bacteria cell and releasing hundreds of new viruses ready to infect more bacteria cells.

C. Used radioactive markers (chemical highlighters) 1. sulfur 35 2. phosphorous 32 **Remember what elements are in A. proteins? B. Nucleic Acids ( DNA)? C H O N S C H O N P

1. Bacteria with phages with either a. radioactive phosphorus OR D. Mixed: 1. Bacteria with phages with either a. radioactive phosphorus OR b. radioactive sulfur 2. Found: Phosphorus radioactivity (which highlights DNA). Did NOT find: sulfur radioactivity (which highlights proteins) E. Hershey and Chase’s conclusion: Genes are made of DNA not proteins. http://nortonbooks.com/college/biology/animations/ch12a02.htm