Name ______________________________
IDENTIFYING THE SUBSTANCE OF GENES
Transformation:
Period ______ Date __________ Seat ____
A process in which one strain of bacteria is changed by a gene or genes from
another strain of bacteria.
GRIFFITH’S EXPERIMENT WITH BACTERIA AND MICE
Deadly
bacteria
(S strain)
Injection
Mouse dies of
pneumonia
Harmless
bacteria
(R strain)
Injection
Mouse lives
Heat-killed
bacteria
(S strain)
Injection
No death
means that a
toxin was not
involved.
Mouse lives
1
Mixture of heatkilled S strain and
live R strain
Griffith’s Conclusion:
Genetic information
could be passed from
one bacterial strain
to another. However,
which molecule
caused the
transformation was
not known.
Injection
Mouse dies of
pneumonia
Live, diseasecausing bacteria
(S strain)
Name ______________________________
IDENTIFYING THE SUBSTANCE OF GENES
Period ______ Date __________ Seat ____
Digestive Enzymes:
Digestive Enzymes
Proteins that break down organic molecules.
Enzyme
OSWALD AVERY’S EXPERIMENT WITH DEADLY
BACTERIA, MICE, AND DIGESTIVE ENZYMES
What it breaks down
Protease
Proteins
Lipase
Lipids (Fats and oils)
Carbohydrase Starches & Sugars
Selected Enzyme
Harmless
R strain
Deadly
S strain
RNAse
RNA
DNAse
DNA
Protease
Dead
Oswald’s
Conclusion:
Lipase
Dead
Carbohydrase
Dead
DNA is the
transforming
molecule
RNAse
Dead
DNAse
Alive!
2
Name ______________________________
IDENTIFYING THE SUBSTANCE OF GENES
Period ______ Date __________ Seat ____
T4 Bacteriophage:
A kind of virus that infects bacteria
Escherichia coli:
A species of bacteria
(the victim)
HERSHEY-CHASE EXPERIMENT WITH
T4 PHAGES AND E. COLI BACTERIA
Hershey and Chase
Conclusion:
DNA is the molecule
of heredity
DNA
E. coli
Grow phages in
medium containing
radioactive 32P
Phage injects its
radioactive DNA
into E. coli
Phage includes
radioactive 32P
in its DNA
Radioactive inside
cell
Protein
shell
E. coli
Grow phages in
medium containing
radioactive 35S
Phage includes
radioactive 35S in
its protein shell
3
Phage infects E. coli,
but protein shell
remains outside cell
Radioactive outside
cell