Download Chapter 12-1 Part 2

Chapter 12-1 Part 2
II. Avery (1944)
A. 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 =
transformation occurred (mouse alive or dead?)
4. Bacteria Extract + RNA destroying enzymes =
transformation occurred (mouse alive or dead?)
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)
A.
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? C H O N S
B. Nucleic Acids ( DNA)? C H O N P
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.
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