Gel Electrophoresis: sort and see the DNA
1. Go to the DNAi website www.dnai.org > Manipulation > Techniques > sorting and
2. View the Gel Electrophoresis 2-D animation, and answer the following questions.
1. How does the process of gel electrophoresis separate DNA fragments?
2. What is the purpose of the agarose gel?
3. What is the purpose of adding blue “tracking” dye to the DNA samples?
4. Explain why DNA has an overall negative charge.
5. Why is the fact that DNA has a negative charge so important in the gel electrophoresis
6. Explain how an agarose gel can separate DNA fragments of different lengths.
7. What is the purpose of ethidium bromide in gel electrophoresis?
8. Why is a marker used when running the fragments through the gel?
9. What is a restriction map?
10. On the final gel photo there are 3 items tested.
(a) Which (1,2 or 3) has the smallest fragment produced by a restriction enzyme?
(b) Which has the largest fragment produced by a restriction enzyme?
11. In one or two sentences, summarize the technique of gel electrophoresis.
Go to www.dnai.org > Applications > Human Identification > Profiling
1. What is a DNA fingerprint?
Go to DNA Variations and Fingerprinting. (The circle with the DNA letters inside)
Click on the “A” DNA variations link. Watch the video and answer the questions.
1. What do the yellow segments represent?
2. What is the genotype of the locus for the male and female shown in the video?
3. What are the possible offspring combinations for the couple illustrated?
On the top of the site click “family”. Read the article.
1. What were Christiana and Andrew trying to prove?
2. Who took on the case to help Christiana and her son prove their relationship?
3. Where was the DNA extracted?
Click on “Try the Comparison”- A.
4. Drag Christiana’s fingerprints to see if they match anyone. Who’s DNA is most similar
Click on the “First DNA fingerprint” and watch the video.
5. When our DNA is cut, what is the name given to the pieces?
6. Complete the sentence: When electricity is applied, ______________ DNA fragments
migrate _____________ through the gel matrix than the _____________ ones.
7. What do the dark bands on the x-ray film represent?
8. How is the DNA fingerprint of one person different from another?