Name: Josh
Status: Student
Grade: 9-12
Location: PA
Country: United States
Date: November 2007
Question:
If Griffith used heat to kill the bacteria in his experiment,
wouldn't the DNA be denatured and therefore would not affect the mice?
Replies:
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.
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