MCAT Question A Day - 5/12/14 - Answer!
In Southern blotting, DNA fragments are separated based upon size during electrophoresis. Which of the following is true of this process?
A. Positively charged DNA fragments move toward the cathode.
B. Positively charged DNA fragments move toward the anode.
C. Negatively charged DNA fragments move toward the cathode.
D. Negatively charged DNA fragments move toward the anode.
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D is correct. Electrophoresis uses an electrolytic cell with a positively charged anode and negatively charged cathode. The phosphate group of the DNA fragment gives it a negative charge tllat is attracted to the positively charged anode.
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