Extracting Strawberry DNA

DNA was a hard topic for my students to grasp because they couldn't SEE DNA.  We watched several videos and looked at many diagrams, but they still didn't understand.

After I attended the NSTA conference I was energized to come back and help my students have a better understanding.

I did this by conducting the Extracting Strawberry DNA (click for link) lab.

Materials (per person) 

 1 resealable plastic bag   (Don't use the cheap ones, you need them to stay together as your mix your solutions)
 Strawberries (fresh or frozen)  (I've only done it with frozen, but I'm going to try fresh next time)
 2 teaspoons of dish detergent  
 1 teaspoon of salt 
 ½ cup of water 
 2 plastic cups (One cup will be used for the filtering apparatus below) 
 Filtering apparatus: coffee filter and plastic cup 
 Ice cold 90 percent rubbing alcohol 
 1 wooden popsicle stick or plastic coffee stirrer 

Procedures 

1. Pull off any green leaves on the strawberry that have not been removed yet. 

2. Put the strawberry into the plastic bag, seal it and gently smash it for about two minutes.  

Completely crush the strawberry. This starts to break open the cells and release the DNA.  

3. In a plastic cup, make your DNA extraction liquid: mix together 2 teaspoons of detergent, 1 

teaspoon of salt and ½ cup of water.  

4. Add 2 teaspoons of the DNA extraction liquid into the bag with the strawberry. This will further 

break open the cells.  

5. Reseal the bag and gently smash for another minute (Avoid making too many soap bubbles). 

6. Place the coffee filter inside the other plastic cup. 

7. Open the bag and pour the strawberry liquid into the filter. You can twist the filter just above the 

liquid and gently squeeze the remaining liquid into the cup.  

8. Next, pour down the side of the cup an equal amount of cold rubbing alcohol as there is 

strawberry liquid. Do not mix or stir. You have just isolated the DNA from the rest of the material 

contained in the cells of the strawberry. 

9. Within a few seconds, watch for the development of a white cloudy substance (DNA) in the top 

layer above the strawberry extract layer.  

10. Tilt the cup and pick up the DNA using a plastic coffee stirrer or wooden stick.

The students watched and helped me do the experiment, but in order to save time and money I conducted the actual experiment.  Afterwards, we took the DNA and looked at it under the microscope.    We couldn't see anything, so students suggested (YAY!!) that we dye it!  

The white floaty stuff are the DNA strands.

Have you done this experiment before?  I've heard it can be done with grapes!!

Teaching Genetics

Another day I'm putting off my to do list.  I just cannot seem to get motivated this summer, even though I had big plans! ;)

Oh well, blogging is important- so that counts, right?

Today I wanted to share a wonderful website that I used when teaching Genetics and Heredity this year.

The website is called Teach Genetics (http://teach.genetics.utah.edu) and is ran by the University of Utah.  Although it is geared for middle and high school students, my fifth graders enjoyed MANY of the activities.

I was introduced to this website during the NSTA conference in Atlanta last November.  It was such a FUN experience!

The website has videos, lessons, pictures, etc.

The Print and Go Lessons are best!

I started out by sharing different traits that they could have, and students marked along using the Inventory of Traits sheet.

Students enjoyed playing the Make a Match Game!  Which got them talking in groups about traits that they had in common with others, and those that they had different.

Another favorite was Generations of Traits.

We were doing our Genetic and Heredity lesson at the beginning of December, so the gingerbread theme worked out great!  Students sorted the pom-poms and recorded the information of their results.

Our favorite activity was creating our own dog!!  Although it took a lot of prep time the students REALLY enjoyed working with a partner and creating their dogs.

After they created their dogs they got to share them with the class.

The website is simply wonderful and I haven't even went over EVERYTHING that it has!  Everything is user friendly and ready to print and use!

What type of lessons do you do for Genetics and Heredity?

BTW: A Wonderful new blog has been created:

And through this: :you could win a blog makeover! So What?? :)