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Chapter 12: DNA “The Blueprint of Life”. Chapter 12.1 (Pg. 338-343): Identifying the Substance of Genes.

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Presentation on theme: "Chapter 12: DNA “The Blueprint of Life”. Chapter 12.1 (Pg. 338-343): Identifying the Substance of Genes."— Presentation transcript:

1 Chapter 12: DNA “The Blueprint of Life”

2 Chapter 12.1 (Pg ): Identifying the Substance of Genes

3 What makes up a gene? -Scientists wanted to understand chemical nature of the gene -Frederick Griffith -Wanted to know how bacteria cause pneumonia in mice -Isolated two similar types (strains) of bacteria -S Strain: causes pneumonia -R Strain: harmless

4 Griffith’s Experiments -Injected mice with different bacteria 1)S Strain: Mouse Died 2)R Strain: Mouse Lives 3)S Strain (Heated): Mouse Lives 4)S Strain (Heated) and R Strain: Mouse Dies What Happened?

5 Transformation -The harmless bacteria changed into the disease causing bacteria -Some ‘chemical factor’ transferred from the heat-killed S Strain cells into the living R Strain cells -The ability to cause disease was inherited by the R Strain

6 What is the Chemical Factor? -1944: Oswald Avery -Mixed heat-killed S strain and R Strain bacteria with different enzymes

7 Hershey-Chase Experiment -1952: Alfred Hershey and Martha Chase -Used bacterial viruses to identify genetic material -Bacteriophage: virus that infects bacteria by injecting its genetic information -Contain DNA core and protein coat

8 Hershey-Chase Experiment -Used radioactive phosphorous and sulfur -Acted as markers -All radioactivity in bacteria was phosphorous -Concluded that genetic material of bacteriophage was DNA

9 The Role of DNA 1)Store Information 2)Copy Information 3)Transmit Information


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