BIOL 1406
PreLab 9a.5
How do I know which E. coli cells have absorbed a recombinant plasmid?
During this lab exercise, you will attempt to transform E. coli cells by mixing
them with 3 different unknown solutions. The strain of E. coli that you will
use (DH5) is killed by ampicillin and does not have the lacZ gene. The 3
unknown solutions will be labeled A, B, and C:
After incubating competent E. coli cells with the 3 unknown solutions described above, the cells will be inoculated on 3 separate Petri dishes containing nutrient agar with ampicillin and Xgal. The Petri dishes will be incubated for several days at 37° C to allow the bacteria to replicate. When placed on nutrient agar, one bacterial cell can divide over and over until there are millions of descendants on the plate. Although one bacterium is not visible to the naked eye, the millions of descendants piled together appear as a shiny dot, called a bacterial colony, on the surface of the agar. |
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Blue and white colonies |
Your Turn | |
After you have incubated your Petri dishes at 37 °C for several days, what do you expect to see in the dish inoculated with E. coli that were mixed with the unknown solution that contained no DNA at all? | Check your answer. |
Explain your answer to the question above. | Check your answer. |
After you have incubated your Petri dishes at 37 °C for several days, what do you expect to see in the dish inoculated with E. coli that were mixed with the unknown solution that contained the normal pUC18 plasmids? | Check your answer. |
Explain your answer to the question above. | Check your answer. |
After you have incubated your Petri dishes at 37 °C for several days, what do you expect to see in the dish inoculated with E. coli that were mixed with the unknown solution that contained the recombinant pUC18 plasmids? | Check your answer. |
Explain your answer to the question above. | Check your answer. |
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