1. Experiments that led to the discovery of DNA
Spark notes Edition

2. Griffith
Experiment:
S strain bacteria injected into mouse -> mouse died
R strain bacteria injected into mouse -> mouse lived
Heated S strain injected into mouse -> mouse lived
Heated S (dead) and alive R strain ->mouse died
Outcome: Cells contain a substance called transforming factor that can change the genome of a host.

3. Avery
Experiment:
S strain bacteria injected into mouse -> mouse died
R strain bacteria injected into mouse -> mouse lived
Heated S strain injected into mouse -> mouse lived
Heated S (dead) and alive R strain ->mouse died
Outcome: When the S strain was heated and killed its DNA was incorporated into the R strains DNA and changed the R strain into S strain.
*Still unknown whether DNA or protein was the “transforming factor”

4. Hershey-Chase
Experiment: Outcome: DNA NOT proteins were the source of genetic material. DNA is the “transforming factor”