Download TRANSFORMATION

What is Transformation?
 When a cell takes up and expresses a new piece
of genetic material—DNA— in order to change
the organism’s traits
 A gene is a piece of DNA which provides the
instructions for making (coding for) a particular
protein
 One of the three processes(other being
conjugation and transduction) by which
exogenous materials may be introduced into a
bacteria
DNA
Protein
Trait
Griffith’s Mysterious Transformation
Experiment
Frederick Griffiths studied the R & S
strains by injecting them into mice
 S injected into mice -> pneumonia -> death
 R injected into mice -> harmless
 Also, boiled S injected into mice -> harmless (bacteria
killed by boiling)
Griffiths did a strange experiment and
got a strange result:
 Boiled S + live R injected into mice -> pneumonia ->
death
 This was not expected because boiled S and live R
were harmless by themselves
 Took blood samples and found live S in the dead mice
 Concluded that some factor, a "transforming
principle", from the dead S had converted some R
bacteria into S bacteria (a genetic change)
E. coli
Escherichia coli is the most common bacterium in the
human gut. It has been extensively studied in the
laboratory and is an important research organism
for molecular biology.
E. coli reproduce very rapidly; a single microscopic cell
can divide to form a visible colony with millions of
cells overnight. Like all bacteria, E. coli has no
nuclear envelope surrounding the bacterial
chromosome and thus no true nucleus. All of the
genes required for basic survival and reproduction
are found in the single chromosome.
Types Of Transformation
(Natural)
 its a bacterial adaptation for DNA transfer , depends
on expression of numerous bacterial genes.
 bacteria must become COMPETENT, a special
physiological state
 Limited to about 67 prokaryotic species(7 diff phyla)
As an adaption for DNA repair
Transformation is induced in Streptococcus pneumoniae
by DNA damaging agents mitomycin C(crosslinking
agent) and fluroquinole(breaks double bonds)
Natural Competence
1% of bacteria is naturally capable of competence under
lab conditions, by a process called horizontal gene
transfer
 Artificial Competence
Involves lab procedures that make the cell passively
permeable to DNA
METHODS
Solution of divalent cations (calcium chloride) under
cold conditions, before the application of heat shock
Electroporation, involves application of 10-20kv/cm,
which creates holes in cell through which plasmid
DNA enters
Basic Principle Of Transformation
 Genes can be cut out of human, animal or plant DNA
 placed inside bacteria and the bacteria will produce
the “foreign” protein coded for by the gene.
 For example, a healthy human gene for the hormone
insulin can be put into bacteria. Under the right
conditions, these bacteria can make authentic human
insulin just as they would make their own proteins.
What is a plasmid?
 A plasmid is a small circle of DNA.
 Ampicillin is an antibiotic; antibiotics prevent
bacteria from growing. Cell membrane
Bacterial
chromosomal
DNA
*plasmids*
Transformation Procedure
TEST TIME!!!
 Place the Stages of Transformation in Order:
C,B,D,E,A
Results
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