Background Information: (Summarize Into 3 Complete Sentences in Your Science NB)

Lab: DNA Extraction Purpose: To extract out and examine the DNA from a group of cells.

Background Information: (summarize into 3 complete sentences in your science NB) DNA is crucial to life; it allows information to be transmitted from one generation to the next. Every cell carries its own copy of DNA and all eukaryotic cells have their DNA stored in the nucleus. Because of its size, a high-powered microscope is needed to view DNA when it is removed from the nucleus.

DNA is squeezed into a small space by a series of compression. First, the DNA is wound around a group of proteins called histones, and then the DNA is further coiled into a tube-like structure called a chromatin, which is finally formed into long hoops and anchored in place by protein. (Think of a telephone cord)

In this lab, we will extract DNA from a group of cells. (The DNA of one cell would be too small to see.) To do this we will use some chemicals that can be found around the house: salt, detergent, and alcohol. The salt and detergent are used to break down the cell membrane, which allows the DNA to be removed. The salt also helps concentrate the DNA by causing it to bind to itself. Finally, DNA has a greater attraction to water than alcohol. The water “pulls” the DNA out of the cell while the alcohol “pushes it”.

Strawberries are soft and easy to pulverize. Strawberries have large genomes; they are octoploid, which means they have eight of each type of chromosome in each cell. Thus, strawberries are an exceptional fruit to use in DNA extraction labs. The soap helps to dissolve the phospholipid bilayers of the cell membrane and organelles. The salt is used to break up protein chains that bind around the nucleic acids. DNA is not soluble in ethanol. The colder the ethanol, the less soluble the DNA will be in it. Thus make sure to keep the ethanol in the freezer or on ice.

Materials: Pureed strawberries Coffee filter Salt water solution 2 beakers 91% Isopropyl alcohol Paper towels Dishwashing liquid Triple beam balance Wooden skewer

Pre-lab Questions: (answer the following in complete sentences in your science NB) 1. What do you expect the extracted DNA to look like? 2. Where is DNA located within eukaryotic cells? 3. Why is DNA an important for living organisms?

Data Table: (copy down and fill in during the lab)

Mass of strawberry puree + cup Mass of cup 1.5 g Mass of strawberry puree Mass of DNA extract % of DNA Procedures:

1. Read all the instructions before your group begins

2. Gather all the necessary materials

3. Using the triple beam balance to find the mass of your pureed strawberries. Record the data “MASS OF STRAWBERRY PUREE+ CUP” onto your data table.

4. Calculate the “MASS OF STRAWBERRY PUREE” by taking the “MASS OF STRAWBERRY PUREE + CUP” – 1.5 g and record onto your data able.

5. Add some salt water to the mixture and mix with a fork. Then add one drop of dishwashing liquid to the puree solution; mix thoroughly.

6. Have one student hold the coffee filter over the opening of the beaker. Have another student slowly pour the mixture into the filter slowly. Strain the solution (be patient!). You may gently squeeze the coffee filter (without letting solid chunks slip through).

7. Slowly add some of the isopropyl alcohol to the filtered mixture.

8. Use the skewer to remove the DNA from the beaker. The DNA is the precipitate (slimy solid) floating on the top.

9. Put paper towel on the triple beam balance and put the DNA onto the balance and weight it. Record the data “MASS OF DNA EXTRACT” onto your science notebook.

10. Calculate the % of DNA inside of your Strawberries by using the following equation:

Record the “% of DNA” onto your data table.

11. Throw away the coffee filter. Pour the liquid solution down the drain where your teacher tells you. DO NOT throw away any of the cups/materials used unless instructed too. Clean-up and make sure lab tables are clean before moving onto the analysis questions.

Analysis Questions: Answer the following questions in complete sentences and make sure to restate the question in your answer. 1. Describe the DNA you extracted. How was the appearance of the DNA similar or dissimilar to what you though at the beginning of this lab?

2. Why is it important for scientists to able to extract DNA from cells?

3. A person cannot see a single cotton thread 100 feet away, but if you wound thousands of threads together into a rope, it would be visible much further away. Explain how this statement is analogous (relates) to what was done in today’s DNA extraction activity.

4. Is there DNA in the food we consume? Use what you learned from the lab activity to explain how you know.