Download Transformation

Playing with Bacterial Plasmids (DNA)
What is it?
 Background:
 1928-Dr. Frederick Griffith studied two forms of S.
pneumoniae
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Pathogenic strain (smooth)- polysaccharide coating
Non-pathogenic (rough)
 Injected into mice:
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Rough: Mice lived
Smooth: Mice died
KILLED smooth: Mice lived
A mix of killed smooth & rough, what should happen?
How could this be?
 DNA had to have been exchanged between the two
types of bacteria
 Transformation: uptake and expression of free DNA by
cells
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Bacteria do this regularly
Have surface proteins that recognize DNA and transport it
into the cell
If enough like the cell’s original, it is used (Recombination)
If not, it is destroyed
We are going to do this
 We will clone a plasmid that contains two special
genes into E. coli:
 One that makes jellyfish glow (pGLOW)
 One that makes bacteria resistant to antibiotics

Ampicillin