Gel Electrophoresis and Analysis - Answer
participating in the classroom dramatization of the process of gel electrophoresis
and the post-activity discussion, answer the following questions.
1. What is the function of each of the following in gel electrophoresis
- Agarose gel:
gel provides a matrix with pores to allow molecules to travel through and
be sorted by size.
- Electric current:
current is the force that causes the negatively charged DNA molecules to more
toward the positive pole.
- "Wells" in the gel:
The wells are the "starting gates"
for the DNA molecules to be loaded into before starting the "race".
2. Toward which pole (positive or negative) does DNA migrate
when electric current is run through the gel? ___positive___
Why do the DNA molecules move toward this pole?
The DNA molecues are negatively charged (opposite
charges attract one another).
3. What would happen to the DNA fragments if you forgot to turn
the current off?
The DNA fragments
would keep on running through the gel until they ran off the end.
4. Describe how different sized DNA fragments are separated
by the gel matrix.
Longer DNA fragments take longer to
work their way through the pores of the gel matrix, they don't travel as far
through the gel as the shorter fragments in the same amount of time.
5. Examine the diagram of an agarose gel below and answer the
- What do the bands in the drawing of the agarose gel represent?
Many DNA fragments which are the same
- Which band(s) traveled slowest?
The bands nearest
the wells (containing the longest DNA fragments) traveled the slowest. (Band
- Which band(s) traveled fastest?
The bands farthest from the wells
(containing the shortest DNA fragments) traveled the fastest.
- On the above drawing, label the positive and negative ends
of the gel.
The negative pole is located closest
to the wells. The positive pole is located furtherst from the wells. SEE DIAGRAM
- How many bands are shared in common by all of the
individuals? 2 (Bands #4 and #9)
- Are there any bands which are unique to only one individual?__yes__
If so, which one? Bands
#6 (sample C) and #10 (sample A).