DNA Extraction Lab - DOC by hcj


									                        DNA Extraction Lab
                        Please do not write on this sheet

         Let’s make DNA Visible
         Stem cells contain all the genes needed to give rise to any of
         the body’s 200 different tissue types, including skin, bone,
         and heart cells. Where are gene stored? Along a double-
         stranded molecule called DNA, which can be found inside
         every cell’s nucleus. Without DNA, stem cells would lack
         their incredible morphing powers.

         Normally, DNA is microscopic because it is encased inside cells, but with the
         right tools, you can make it visible.
         In this experiment, you will extract real DNA from the different foods.

         Food sources                                          Dropper
         liquid detergent                                      Stirring rod
         14 mL rubbing alcohol (90% ethanol)                   Filter paper
         20mL hot tap water (50-60 degrees Celsius)            Mortar and Pestle
         50mL test tube
         Graduated cylinder

   1. Place small portion of food in mortar. Grind using pestle for about 1 minute (until food is
      all mushy)

   2. Place food source in test tube

   3. Add 20mL of soapy water

   4. Mix gently (about 5 seconds) every one minute for 5 minutes.
   (Try not to create any foam, but if you do – use a dropper to remove it.)

   5. Tilt the test tube at a 45 degree angle and slowly and gently pour 15mL
   of ethanol down the side of the test tube so that it forms a
   separate layer on top of the solution.

                            DO NOT mix the solutions together.

DNA separates from the food at the water-alcohol boundary. If alcohol mixes with water, the
solution will become too diluted and the DNA will not precipitate (form).

   6. Let the test tube sit for a few minutes. White, stringy, DNA (looks like
      mucus) will begin to appear at the water-alcohol boundary. After 5-10
      minutes, the DNA will float to the top of the alcohol layer.
Analysis Questions
Answer each question in a complete sentence on a separate sheet of paper.

1. Would you be able to extract DNA from animal cells using
   these methods?

2. Why do we add detergent to the test tube? (Hint: Soap
   contains enzymes.)

3. What does “precipitate” mean?

4. What is left in the bottom of the test tube after the DNA has
   been extracted?

5. What does the alcohol do? Why does the DNA rise to the
   top after adding alcohol?

6. What part of the cell does the DNA come from?

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