Gel electrophoresis is a laboratory technique used to separate and analyze diffe
ID: 528601 • Letter: G
Question
Gel electrophoresis is a laboratory technique used to separate and analyze different types of mixtures of molecules.
a. (1 point) Which two factors does this technique use to separate mixtures of molecules?
b. (1 point) Which factor would be most prominent in separating a mixture of nucleic acids from proteins of the same relative size? Why?
2. (1 point) Based on the structures of bromophenol blue shown at pH 7.4, toward which electrode (positive or negative) will the molecules move when the electric current is turned on? (note: counterions like Na+ and Cl– dissociate from the dye molecules in solution and have no effect during electrophoresis).
3. (1 point) Loading dyes are used in small amounts to make it easier to pipet the sample into the wells of the gel. Sometimes these dyes contain a small amount of a concentrated sucrose solution to increase the sample’s density so that it sinks to the bottom of the well (see picture). When the current is turned on, what do you suppose happens to the sucrose? Explain your answer.
Explanation / Answer
1. A) The two factors that this technique uses to separate mixtures of molecules are:
i. Size (molecular weight)
ii. net charge
B) Charge would be the most prominent factor useful in separating a mixture of nucleic acids from proteins because they are of the same relative size.
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