Essay about Biology Lab

2370 Words Jun 1st, 2008 10 Pages
IB SL Biology Lab

Molecular Biology:
Transformation and Electrophoresis

Christina Qi
2/16/07

Aim:
How can a plasmid be engineered to include a foreign piece of DNA and how does gel electrophoresis separate DNA molecules present in a mixture?


Hypothesis:
If the pGLO plasmid is inserted into competent Escherichia coli cells, then the transformed bacteria will be resistant to ampicillin and will glow green under UV light. If samples of DNA are cut using certain restriction enxymes and separated using gel electrophoresis, then the smaller the DNA fragment cut, the greater the distance it will travel in the gel.

Variables:
The control plates used in transformation are the LB and second LB/Amp plates marked
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• The LB/Amp/ara, and one of the LB/Amp plates marked with a “+” are the experimental plates.
• The LB and second LB/Amp plates marked with a “-“ are the controls.
7. Following 10 minutes of incubation on ice, “heat shock” the bacterial cells. Remove tubes from the ice and immediately immerse them in the 42° C water for 50 seconds. Return the tubes immediately to the ice for 2 minutes.
8. Use a sterile transfer pipette to add 250 μl of Luria broth (LB) to the tubes. Gently tap the tube with a finger to mix, and set the tubes in the cup (without the ice) at room temperature for 10 minutes to recover.
9. Use a sterile transfer pipette to add 100 μl of cell suspension from the “+” culture tube onto your LB/Amp/ara and LB/Amp plates. Then, using a new sterile transfer pipette, add 100 μl of cell suspension from the “-“ culture tube onto your LB/Amp and LB plates. Remember to only open the lid enough to get the tip of the pipette inside to deposit the 100 μl to prevent possible contamination of the culture by bacteria in the air.
10. Using a new inoculation loops, immediately spread the cells over the surface of the plates.
• Use one loop to streak the two positive plates. Use a second loop to streak the two negative plates.
• To streak, lift the plate lid only enough to get the loop inside, move the loop through the culture and the over the surface of the agar as evenly as possible.
11. Invert the plates and…