At the end of our DNA unit, we learn about DNA fingerprinting and how it is used in forensic science. This really hooks students- they feel like real crime scene investigators! I’ve compiled some teaching resources and general lab tips if you plan to teach about DNA fingerprinting and run gels with your students.
DNA Fingerprint Teaching Resources
- DNA Fingerprint Powerpoint: This powerpoint gives students an overview of what a DNA fingerprint is, and how gel electrophoresis works. You can download it FREE here.
- Nonfiction Article: We know animals have unique DNA fingerprints, but do plants as well? This is an engaging article that discusses the first time plant DNA was used in a criminal court case. A Palo Verde tree pod was used in Phoenix in 1992 to link a suspect to a murder. There are 2 versions available (higher and lower lexile) that can be found here.
- Video Clip: This 2 minute video clip is pretty basic, but it helps students visualize the process of DNA fingerprinting before you get to the actual lab. You can find it on Youtube.
- Virtual Lab: Don’t have access to gel electrophoresis equipment? Use this virtual lab instead. This one from HHMI biointeractive is also great!
Gel Electrophoresis Tips
Planning on having students run gels? If you haven’t done this lab in a while, here are some tips:
- First, make sure you have all the necessary hardware. This includes the gel box with wells, combs, power supply boxes, and pipettes with sterile tips. Bonus if you have light boxes to view the gels at the end of the lab. (This gets expensive…. donors choose is your best friend).
- Have students practice how to use pipettes the day before the actual lab. It is hard enough to use them properly, on top of loading it into the well without breaking your gel. The first thing I do is mime it out with students. Hand them a pipette and help them set the volume, and practice pushing down halfway and all the way. They really need to get the feel of it before doing the actual lab. Also, I came across this fun way to practice using pipettes by doing “pipette art.” Check it out!
- Order a kit that has EVERYTHING you need: agarose, buffer, DNA, restriction enzymes, and dye. Here is one from Wards Science I have used in the past. (Some kits come with the DNA sample already cut into fragments so you don’t have to spend an extra day adding the enzymes). Don’t try and piece together the lab with buffer or dye you already have laying around and risk the lab not working properly. Also important to note- nutrient agar is NOT the same thing as agarose.
- Prepare your gels a day or two before class. Make sure you use the same type of buffer to make your gels as you use to run your gels. You cannot mix and match buffers. Once they are set, slide them into a Tupperware container full of buffer and leave in the fridge until they are ready to use. (This buffer can be reused when you run your gels, so it won’t go to waste).
- Tip: If you have short class periods, pour thinner gels. The thinner the gel, the quicker they will run. If you are on block schedule you will have plenty of time, but if you have 50 minute classes you will be cutting it VERY close.
- Overall, my week tends to look like this:
- Day 1-2: Learn about gel electrophoresis and do a paper or virtual lab.
- Day 3: Pipette practice (and add your restriction enzymes to your DNA if your kit requires).
- Day 4: Load and run your gels. At the end of class, add stain.
- Day 5: Destain gels, and observe on light boxes.
I hope these resources and tips help you have a smooth lab day!
Rock on,
