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“The Blueprint of Life”

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Presentation on theme: "“The Blueprint of Life”"— Presentation transcript:

1 “The Blueprint of Life”
Chapter 12: DNA “The Blueprint of Life”

2 Chapter 12.1 (Pg. 338-343): 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 S Strain: Mouse Died R Strain: Mouse Lives S Strain (Heated): Mouse Lives 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 Store Information Copy Information
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