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General DNA Extraction Method

 (Adapted from The Genetic Learning Center)


Combine in a blender:     50 mL DNA source

                                            1/8 tsp. salt

                                            100 mL cold water  


Blend 15 seconds on high speed.

Strain the mixture into a beaker.

Add 1 Tbsp. dish detergent.

Swirl mixture gently.

Let stand 10 minutes.

Transfer mixture to 3 test tubes.

Tilt each test tube slightly.

Slowly pour isopropyl alcohol into the test tube to form a layer.

Record observations immediately, and in 24 hours. Store in fridge.

Weigh extracted DNA after 24 hours.

How Does This Method Work?
The blending breaks down the cells of the DNA source.
The salt provides the DNA with a favorable enviroment.
The detergent breaks down the two sacks: cell membranes and the nucleus. The enzymes in the soap break down the molecules and the membranes and release the cell contents which include the DNA. Almost all of the DNA is from the cell nucleus.
To one of my experiments I added a pinch of meat tenderizer. This product contains enzymes which are also proteins. Proteins help break up the cell membrane.
The isopropyl alcohol does not dissolve the DNA which floats up to the top. The material at the bottom of the test tube is cell scum.



Wheat Germ DNA Extraction Protocol

 (Adapted from The Genetic Learning Center)

Used in Experiment Five only


Place 1 tsp wheat germ in graduated cylinder
Add 1.5 Tablespoons of tap water, stir for 3 min
Add 1/4 tsp liquid detergent. Mix every half minute for 5 minutes, trying not to create foam.
Tilt the cylinder and slowly add 1 tablespoon of alcohol so it forms a layer.