Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Killing bacteria with Heat and DNA
Name: Josh
Status: Student
Grade:  9-12
Location: PA
Country: United States
Date: November 2007

If Griffith used heat to kill the bacteria in his experiment, wouldn't the DNA be denatured and therefore would not affect the mice?

The smooth bacteria were killed by the heat. He did not heat kill the rough bacteria. when DNA is denatured it isn't the same thing as denaturing protein. Denaturing disrupts hydrogen bonds holding the molecule together. In proteins this destroys the tertiary structure (3D shape) which destroys its function. In DNA this breaks the two strands of the double helix apart into single strands. When Griffith mixed the two types of bacteria together in the same tube, the rough bacteria were able to scavenge the smooth bacteria's DNA and take portions into its own DNA by recombination. In other words, the rough bacteria took in a portion of the smooth DNA and exchanged it with its own DNA for that portion. This gave it a gene it didn't have on its own and allowed it to survive the mouse's immune system so it wasn't killed. This process of one bacteria taking in genes from its surroundings is called transformation.


Click here to return to the Molecular Biology Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory