Name______Period ______Date ______
Gel Electrophoresis
A Case Study of Paternity Analysis
Introduction:
Gel electrophoresis is a biotechnology technique that separates DNA according to their charge and size. It is frequently used to analyze samples of DNA. In this laboratory activity, agarose gel electrophoresis will be used to separate and characterize colored dye molecules of various sizes and charges.
Once all the DNA samples have been loaded into the wells, the chamber is connected to a power supply and an electrical current is applied to the gel. The chamber is designed with a positive electrode (anode) at one end and a negative electrode (cathode) at the other end. Molecules with a net negative charge migrate toward the positive electrode and molecules with a net positive charge migrate toward the negative electrode because opposite charges attract.
The overall charge of a molecule affects the speed at which it travels through the gel. The size and shape of the molecule also affects how quickly it travels through the gel. Agarose gels contain a matrix of minuscule pores that acts like a sieve. Small molecules maneuver more easily through the pores of the gel than larger molecules, allowing them to migrate quickly.
Purpose:
In this lab we will be investigating the DNA of 2 males and 2 females along with 3 children. We will need to find out which child belongs to which male/female pair using Gel Electrophoresis. Some of the dyes will be attracted to the negative electrode and some to the positive electrode depending on their overall charge. Each of the known dyes will exhibit a unique gel migration distance that relates to its molecular size and net charge. You will identify the components of the unknown dye mixtures by comparing the migration distances and direction of migration of the unknown dyes to those of the known dye samples.
Materials:
· Agarose gel
· Electric current chamber with power adapter
· DNA dyes
· Micro pipettes
· Gloves
· Metric ruler
· Colored pencils
Procedure:
1. Put on gloves. You may be sharing dye samples and the agarose gel with another lab group.
2. On the gel load 5-10 µl of each dye into a well. Keep track of which dye goes into which well on a notebook sheet. Use a new tip for each dye and be careful not to puncture the bottom of the well.
3. Thoroughly clean up any spilled buffer or any other liquid surrounding the gel box.
4. Make sure that the power supply is unplugged and switched off before proceeding.
5. Plug in the power supply, select the 30 min option and turn on the machine. The run light will illuminate, signifying that power is running to the cell.
6. Let the gel run undisturbed for about 30 minutes but check frequently to determine that the dyes will not run off the end of the gel into the buffer compartment.
7. Clean up you work area and use your gel to complete the data tables and questions.
Data 1:
*Make sure to correctly record which lane in the gel you loaded the persons DNA into*
*If the color did not leave the well or migrated behind it mark the data as 0*
Male 1 (Bob)
Female 1 (Jane)
Male 2 (Harry)
Female 2 (Ruby)
Child 1
Child 2
Child 3
Data 2: Using color, draw in your bands on the gel. Label each well with the given sample.
Analysis
Using data, conclude with your research which child belongs to which male/female.
Baby / Parent 1 / Parent 2Child 1
Child 2
Child 3
Analysis Questions
1. Explain how you were able to figure out the parents from your data. (List which bands matched child to parent)
2. How is DNA and the gel electrophoresis method useful in science?
3. Why do we need to plug the chamber into an electric current?
4. How is the DNA arranged on the gel after electrophoresis? Where do the short strands end up?
5. What did you learn by completing this lab? Were there any errors in completing this lab?