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Copy of 12.1 Identifying the Substance of Genes
Transcript of Copy of 12.1 Identifying the Substance of Genes
Why did the last mouse die???
Both the heat-killed S cells and the R cells by themselves were harmless but when they were mixed together they killed the mouse.
Griffith concluded that the heat killed- S cells must have passed their disease-causing ability to the R cells.
S strain vs. R strain
The "S" stands for SMOOTH
The S strain colonies caused pneumonia
Think: S Sick
Griffith called this process transformation because one type of bacteria (harmless) had been changed or "transformed" into another type (harmful).
In 1944, Oswald Avery and a team of scientists wanted to know which molecule was responsible for transformation that Griffith observed in his experiments.
Avery found out that when DNA was broken down in the heat killed-S cells, transformation would NOT occur.
12.1 Identifying the Substance of Genes
In 1928, Griffith was trying to figure out how a certain type of bacteria gave people pneumonia.
He isolated two very similar types of the same bacterial species.
One caused pneumonia, one did not
The "R" stands for ROUGH
The R strain colonies DID NOT cause pneumonia
Make predictions on your guided notes!!!
Avery concluded that the nucleic acid
stores and transmits genetic information from one generation of bacteria to the next!
In 1952, Alfred Hershey and Martha Chase studied
in order to determine whether it was DNA or protein that was the genetic material.
= a type of virus that infects a bacterial cell or
Hershey and Chase used radioactive markers to "label" DNA and protein in the bacteriophage.
Phosphorus-32 for DNA
Sulfur-35 for protein
Hershey and Chase's experiment with bacteriophages confirmed Avery's results, convincing many scientists that
was the genetic material found in all living things.