Name: Loretta L Lamb
I've been telling my students about Fred Griffith's experiment
and DNA transformation, but when I get to the idea of the rough pneumococcus
actually taking the genes from the smooth and thereby transforming itself
into a virulent strain, the question always arises in my mind (although usually
NOT in my STUDENTS' minds) about the mechanism for this. How exactly did the DNA
from the rough obtain those key DNA sequences from the smooth? How did it
enter the rough's genome? I imagine that the heat treatment to kill the
smooth probably disrupted their capsules, but that still doesn't explain how
the rough obtained the DNA from the smooth. Can you help?
Are you familiar with transformation experiments in genetic engineering?
Many bacteria can take in DNA from the environment,
given the right conditions. If the DNA from the smooth were
left floating around in the environment after the capsules were
disrupted, then at least some of that DNA could be taken into the
rough bacteria. Apparently, the "right" segments of gene(s) got
in to transform those remaining intact bacteria. Then, they could
reproduce, forming lots of virulent "offspring." Does that make
sense to you?
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Update: June 2012