What did Griffith, Avery, and others demonstrate with bacteria?

What did Griffith, Avery, and others demonstrate with bacteria?

• A. Proteins determine inherited traits.
• B. RNA determines inherited traits.
• C. Dead bacteria cannot influence live bacteria.
• D. DNA is the transforming principle causing changes in live bacteria.

Answer: (D)

The main idea being tested is that DNA can carry and transfer heritable information between bacteria, through a process called transformation. Griffith’s experiments showed that a dead, virulent strain could transfer its genetic material to live, nonvirulent bacteria, turning them into virulent form. This indicated that something from the dead cells—later called the transforming principle—was capable of altering the phenotype of the living cells. Avery, MacLeod, and McCarty refined this by identifying the transforming substance itself. They demonstrated that destroying DNA in the transforming extract prevents transformation, whereas destroying proteins or RNA does not. This pinpointed DNA as the material responsible for heredity in this bacterial system. Together with later work like Hershey and Chase, these findings established DNA as the genetic material, not proteins or RNA, and showed that genetic information can be transferred between cells via DNA. So the correct idea is that DNA is the transforming principle causing changes in live bacteria.

The main idea being tested is that DNA can carry and transfer heritable information between bacteria, through a process called transformation.

Griffith’s experiments showed that a dead, virulent strain could transfer its genetic material to live, nonvirulent bacteria, turning them into virulent form. This indicated that something from the dead cells—later called the transforming principle—was capable of altering the phenotype of the living cells.

Avery, MacLeod, and McCarty refined this by identifying the transforming substance itself. They demonstrated that destroying DNA in the transforming extract prevents transformation, whereas destroying proteins or RNA does not. This pinpointed DNA as the material responsible for heredity in this bacterial system.

Together with later work like Hershey and Chase, these findings established DNA as the genetic material, not proteins or RNA, and showed that genetic information can be transferred between cells via DNA.

So the correct idea is that DNA is the transforming principle causing changes in live bacteria.