BIO208
PRE-LAB for Laboratory Exercise 6
Electrophoresis of the PCR Product
Read the Electrophoresis Lab Ex6 pages 1 - 4
1. From what kind of organism is the non-toxic gel substance, agarose, obtained?
Agarose comes from boiled red algae.
2. Agarose is weighed and placed into water. This is a weight/volume relationship. If 1 gram of
agarose in 100 ml water = 1% (w/v). How much agarose is required to make 50 ml of a 0.8%
(w/v) gel?
0.8 % = 0.8g/100ml 0.8/2= 0.4g of agarose
3. What are 2 factors that affect the rate of migration of DNA though a gel?
Size of DNA molecules, and voltage.
4. Review the DNA fingerprinting lab to find out what approximate size (in kilobases, kb) DNA
molecules are obtained via the PCR. According the table shown on page 2 of the
Electrophoresis lab, what would be a typical % agarose to use?
0.3 kb 1.5% agarose
5. Research to find out what TAE buffer is. What do the letters stand for?
TAE stands for Tris base, acetic acid, and EDTA.
6. How do you make 500 ml of 1X TAE buffer from a 20X stock solution? (how much TAE,
how much water is added) (note: this is a volume/volume relationship.)
20/0.05= 1 0.05 ml of TAE stock in a 500 ml solution.
7. DNA is negatively charged due to the phosphate backbone. In what direction does DNA
move through an agarose gel?
a. From the red to the black electrode
b. From the negative to the positive electrode
c. From the anode to the cathode
d. From the comb to the black electrode
https://www.youtube.com/watch?v=vq759wKCCUQ BioRad 4 minutes
Note that the blue dye used in the sample is referred to as “tracking dye”. Tracking dye has a
high density which allows the sample to flow into the well.
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