4.06 Genetic Park: Honors DNA Lab

The Honors student will:

• apply basic DNA extraction procedures to view DNA
• analyze the purpose of materials used in DNA extraction procedures
• have an opportunity to do an Above and Beyond experiment in which you design further investigation of the DNA extraction procedure and report the outcome

Here is your chance to join our laboratory team at Genetic Park. We need some DNA for some experiments and we would love your help. In this activity you'll put your skills to the test and have some fun doing it. So jump right in and get started.

DNA Extraction from Wheat Germ

Here We Go...

This method yields large quantities of DNA that can be easily collected.

Here's what you'll need for each DNA extraction:

Materials Needed:

• Raw wheat germ - 1 gram or 1 teaspoon.
  Wheat germ can be purchased at grocery stores (usually near the flour/baking area or breakfast foods) or you can get it at a health food store; toasted wheat germ does not work.
• Liquid detergent - 1 ml or a scant 1/4 teaspoon.

  (Note: you can use a medicine syringe from the pharmacy to measure ml.)

  The following liquid soap products have been tested and found to work well for this DNA extraction lab: Lemon Fresh Joy, Woolite, Ivory, Shaper, Arm & Hammer, Herbal Essence shower gel by Clairol, Tide, Dish Drops, Kool Wash, Cheer, Sunlight Dish Soap, Dawn, Delicate, All, and Ultra Dawn.

  The following liquid products do not work well: Life Tree, Shout, Shaklee, Sunlight Dishwasher, and LOC. Powdered detergents also do not produce good results with this protocol.

• Alcohol - 14 ml or 1 tablespoon 70% isopropyl alcohol.

  Rubbing alcohol is the least expensive since it can be purchased at a grocery store or pharmacy. However, it contains a higher percentage of water, making it slightly more difficult to precipitate the DNA. A precipitate is a solid that forms from a solution.

• 50-60° Celsius tap water - 20 ml or 1 tablespoon.

  Do not use water hotter than 50-60° C or 122 F-140 F. Water boils at 100 C or 210 F. Water should NOT be boiling. The temperature of the water can make or break the experiment. It is VERY important to be in the range. The water will cool during the extraction procedure, but this does not matter. Test your tap water. It may be hot enough right from the tap. (My tap water was just about hot enough. I put my hot tap water in the microwave for 10-15 seconds.) If you do not have a thermometer, just try the hot water from your faucet.

• 50 ml test tube or baby food jar.

  Pick up some apple sauce to snack on before the lab...Just remember to wash it!

• Measuring spoons, medicine syringe, or other measuring devices.
• Wooden applicator stick,

  Glass stirring rod/hook, paper clip hook, or shish kebob skewer for stirring and collecting the mixture.

• Eyedropper

  Eyedropper with a bulb on the end or pieces of paper towel - may be needed to remove foam

• Paper towels or filter paper (coffee filters will work) - for drying DNA
• Kitchen scale (optional)

  This can tell you how much DNA you have and can be used to compare different techniques.

Instructions

1. Place 1 gram or 1 teaspoon of raw wheat germ in a 50 ml test tube, beaker, or jar.
2. Add 20 ml or 1 tablespoon of hot (50-60° C or 122 F-140 F) tap water and mix constantly for 3 minutes.
3. Add 1 ml or a scant 1/4 teaspoon of detergent and mix gently for 5 minutes. Try not to create foam.
4. Use an eyedropper or piece of paper towel to remove any foam from the top of the solution. (Hint: Use ½ piece of paper towel and fold it a few times to make a stiff rectangle shape. This will give you more control and work better)
5. Tilt the test tube or jar at an angle. SLOWLY pour 14 ml or 1 tablespoon of alcohol down the side so that it forms a layer on top of the water/wheat germ/detergent solution. (Hint: Make sure when you add the alcohol it touches the side of the jar and NOT the mixture.) Do not mix the two layers together. DNA precipitates at the water-alcohol interface (the boundary between the water and the alcohol). Therefore, it is crucial to pour the alcohol very slowly so that it forms a layer on top of the water solution. If the alcohol mixes with the water, it will become too dilute and the DNA will not precipitate.
6. Let the test tube or jar sit for a few minutes. White, stringy, filmy stuff will begin to appear where the water and alcohol meet. THAT IS DNA! You will usually see DNA precipitating from the solution at the water-alcohol interface as soon as you pour in the alcohol. If you let the preparation sit for 15 minutes or so, the DNA will float to the top of the alcohol.

   You can usually get more DNA to precipitate from the solution by using one of the DNA-collecting tools (such as a glass or paper clip hook) to gently lift the water solution up into the alcohol. This allows more DNA to come in contact with the alcohol and precipitate. You may find it helpful to pour the water/detergent solution into a clean test tube, leaving behind the wheat germ, before adding the alcohol.

7. Use a glass or paper clip hook or a wooden stick to collect the DNA.

   It looks something like this:

   

Click here for a printable version of the information above.

Above and Beyond Activity: Be a Real Scientist

At the Learn Genetics site there are some optional activities. To earn up to 10 Above and Beyond points, complete one additional activity described there.

To find the activities:
When the site opens look over to the bottom left section of the page to find "Virtual Labs." Read through the suggested activities.

For up to 10 points extra credit:

• Choose and complete one activity.
• Write a summary of the procedure and the results and you will have the opportunity to submit with the assessment.

Resource site: Learn Genetics