Presentation on theme: "GRIFFITH’S EXPERIMENT SWBAT identify DNA as the transforming agent."— Presentation transcript:
GRIFFITH’S EXPERIMENT SWBAT identify DNA as the transforming agent
WHAT DO YOU KNOW ABOUT DNA?
BEFORE GRIFFITH Scientists knew DNA was made of phosphate- sugar-base Did not know the structure or role DNA had been identified but not understood In 1927 Kolstov proposed there was the hereditary molecule Did not know which molecule was hereditary (DNA)
FREDERICK GRIFFITH ( ) Worked in a very basic lab with cheap equipment “Could do more with a kerosene tin and primus stove than most men could do with a palace” Was an expert on Pneumococcus Collected samples from patients all over England
PNEUMOCOCCUS: BACTERIA Has two forms: Rough (R) and Smooth (S) Rough is nonvirulent doesn’t cause illness Smooth is Virulent; Makes people sick Can be killed by heat
GRIFFITH’S EXPERIMENTS Injected mice with live R Pneumococcus: Mice lived Injected mice with live S Pneumococcus: Mice died Injected mice with heat-killed S Pneumococcus: Mice lived Injected mice with live R and heat-killed S Pneumococcus: Mice died
AFTER GRIFFITH’S EXPERIMENT Scientists first thought Griffith messed up Later these experiments were redone and were proven right