Worksheet 8
Colony Transformation
20 points
Name:
Section:
Date Turned in:
Introduction:
1. (3 pts) Why could the E.coli in this lab be classified as a “Genetically Modified
Organism (GMO)”?
2. (2 pts) Based on your lab manual, what cellular or biochemical mechanism
makes E. coli unable to grow in the presence of ampicillin?
Materials and Methods:
3. (2 pts) What was the rationale behind creating the culture labeled –WT?
4. (2 pts) Would it matter to the results if you added the pAMP to the +T tube after
the heat shock step? Why or why not?
5. (2 pts) Does pAMP contain ampicillin? Explain why or why not.
Results:
6. (4 pts) We added 10 l of 0.005 g/l of pAMP to a suspension of E. coli. The
cells were suspended in 200 l of cold CaCl2 and 200 l of Luria broth. After heat
shock at 42oC, the cells recovered at room temperature. 100 l of suspension was
placed on agar plates. The plates were incubated at 37oC for 24 hours. We
observed 2015 colonies of E.coli on the ampicillin plate. Calculate the
transformation efficiency and give your answer in scientific notation. Show your
answer below, write work on the back or another handwritten piece of paper and
use correct units!
Discussion
7 (3 pts) Your lab partner tells you that there was no growth on the +WT plate
because the heat shock step actually killed the bacteria. Using the results on your
plates as evidence, prove that he/she is wrong. Note: the answer is not “because
the amp killed it”, you need to convince your lab partner, using evidence, that he
or she is incorrect.
8. (2 pts) Here are the transformation efficiencies from a Bio 1 lab in Spring 2015.
Assume the following:
all of the groups started with living E.coli on starter plates,
all of the groups followed the procedure in the lab manual,
there was no contamination of the plates
there was no “human error”.
Why would there be such a range of results? In other words, what parts of the
procedure might be interpreted differently by each group that could result in such
variation?
Group 1:
5.6 x 103 col/ug
Group 4:
9.1 x 103 col/ug
Group 2:
1.4 x 105 col/ug
Group 5:
5.0 x 104 col/ug
Group 3:
2.2 x 102 col/ug
In your answer, provide the source of variation and why/how it would
cause each group to get different data.