Lab Work Mystery Cache

Key Concepts:

DNA

Genome

Genes

Extraction

Laboratory procedures

 

Introduction:

Have you ever wondered how scientists know so much about DNA? Something that is so small that it all fits into one and every cell. Well, the first thing that is needed in order to study it is to isolate the DNA and extract it from cells. All living organism have DNA (deoxyribonucleic acid). DNA is the blueprint of life and tells an organism how to develop and function. DNA is one of the most complex chemical compounds and it is found in literally everything that is living. 

To get the coordinates for this geocache you’ll make your own DNA extraction kit from household chemicals and use it to separate DNA from strawberries. Answer the questions as you go along to solve the coordinates at the end of the experiment. 

 

Background:

Whether you’re a human, rat, tomato, or bacterium, each of your cells will have DNA inside of it. Each cell has an entire copy of the same set of instructions, and this set is called the genome. To get the DNA from a cell, scientists typically rely on one of many DNA extraction kits available from biotechnology companies. During a DNA extraction, a detergent will cause the cell to pop open, or lyse, so that the DNA is released into solution. Then alcohol added to the solution causes the DNA to precipitate out. In this activity, strawberries will be used because strawberries are octoploids; meaning they have eight copies of the genome, giving them a lot of DNA per cell.

 

Material:

• Rubbing Alcohol

• Measuring Cup

• Measuring Spoons

• Salt

• Water

• Dishwasher Liquid (for Hand-Washing Dishes)

• Glass or Small Bowl

• Cheesecloth

• Funnel

• Tall Drinking Glass

• Three Strawberries (More if you want a snack)

• Resealable Plastic Sandwich Bag

• Small Glass Jar (such as baby food jar)

• Bamboo Skewers

 

Preparation:

• Chill the rubbing alcohol in the freezer (you’ll need it later).

• Mix one half teaspoon of salt, one third cup of water and one tablespoon of dishwashing liquid in a glass or small bowl. Set the mixture aside. This is your extraction liquid.

• Completely line the funnel with cheesecloth. Insert the funnel tube into the tall drinking glass (not the glass with the extraction liquid).

• Remove and discard the green tops from the strawberries.

 

Procedure:

0. Put the strawberries into a resealable plastic sandwich bag and push out all the extra air. Seal the bag tightly. Why are we using strawberries in this experiment?

1. With your fingers, squeeze and smash the strawberries for two minutes. How do the smashed strawberries look?

2. Add three tablespoons of the extraction liquid you prepared to the strawberries in the bag. Push out all the extra air and reseal the bag. How do you think the detergent and salt will affect the strawberry cells?

3. Squeeze the strawberry mixture with your fingers for one minute. How do the smashed strawberries look now?

4. Pour the strawberry mixture from the bag into the funnel. Let it drip through the cheesecloth and into the tall glass until there is very little liquid left in the funnel (only wet pulp remains). How does the filtered strawberry liquid look?

5. Pour the filtered strawberry liquid from the tall glass into the small glass jar so that the jar is one quarter full.

6. Measure out one-half cup of cold rubbing alcohol.

7. Tilt the jar and very slowly pour the alcohol down its side. Pour until the alcohol has formed approximately a one-inch-deep layer on top of the strawberry liquid. You may not need all of the one-half cup of alcohol to form the one-inch layer. Do not let the strawberry liquid and alcohol mix. What does the alcohol do to the mix of strawberry goo?

8. Study the mixture inside of the jar. The strawberry DNA will appear as gooey clear/white stringy stuff. Do you see anything in the jar that might be strawberry DNA? If so, where in the jar is it?

9. Dip the bamboo skewer into the jar where the strawberry liquid and alcohol layers meet and then pull up the skewer.  Did you see anything stick to the skewer that might be DNA? Can you spool any DNA onto the skewer?   

 

Solving Geocache Coordinates

N  043° 59. [Red Juicy Pulp With Bubbles][Red Juicy Pulp with Bubbles][Forms Precipitation of DNA]

W 123° 21. [They are Octoploids][Forms precipitate of DNA][Red and gooey]