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Bacterial Transformation
1. Analyze What does the genome of a transformed E. coli cell contain that a normal E.
coli cell does not contain? Based on your observations, how can you tell which, i f any, of
the bacterial cells were transformed?
<The genome of the transformed bacterial cells incorporated the amp"* gene into their
genome. Normal E. coli cells do not grow in the presence of ampicillin. The amp*^ gene
allows bacteria to grow when exposed to ampicillin. Transformed cells are resistant to
ampicillin. Only bacteria resistant to ampicillin can grow on the media that contains it.
The cells that were observed growing in the presence of ampicillin incorporated the amp'^
gene. The cells that did not incorporate the amp" gene were unable to live in the presence
of ampicillin.>
2. Compare and Contrast Which Petri dish(es) showed the most growth and which
showed the least?
<The Petri dish without ampicillin in the agar for both +amp" and -amp" bacteria grew
the most and equally. There was no growth for ampicillin agar and -amp". There was
partial growth in the Petri dish with ampicillin in the agar for the +amp" bacteria.>
3. Infer What does the culture with partial growth tell you about whether all of the
bacterial cells incorporated the amp" gene?
<Partial growth of the amp" bacteria in the presence of ampicillin shows that only some
of the bacteria that were treated actually took in the recombinant DNA.>
4. Evaluate Look at the two Petri dishes that had the most growth. What do they have in
common? Explain why the amp" gene offers or does not offer an advantage when grown
in the environment of these Petri dishes.
<Neither of the Petri dishes contained the ampicillin antibiotic. In this environment the
amp" gene offers no advantage because there is no ampicillin present to which the
bacteria needs resistance.>
5. Conclude How does the Petri dish that showed no growth support the conclusion that
some bacterial cells did take in the amp" gene?
<The medium in the Petri dish that showed no growth contained ampicillin. The bacteria
that were grown on that medium did not have the amp" gene, therefore, they had no
resistance to the antibiotic and were not able to grow. This served as a control for the
experiment. The other Petri dish with medium that contained ampicillin did have living
bacteria. The bacteria that could live in the presence of ampicillin did so because they
incorporated and expressed the amp" gene. By comparing these two Petri dishes one can
tell the effect of changing just one variable, in this case, the presence or absence of the
amp" gene.>