Finding fruit DNA
Praxis is quite excited to be celebrating our 30th annual Operation Minerva Conference on Thursday, March 10!
Each and every year we have such an amazing group of
Grade 9 girls from all over southeastern Alberta. I can also proudly say some of the girls that participated in the conference are now my mentors! It is so exciting to see so many
STEM professionals return to our wonderful community to work. This year we had to go virtual, but we will be doing an amazing interactive experiment. I thought I would share it here so you can get an idea of what we will be doing. If you did not receive registration forms from your teacher, do reach out to Praxis so you do not miss the deadline of March 1. Let’s get started!
Remember to ask an adult before doing this experiment.
Materials
• Safety goggles
• Ice
• Water
• Measuring spoons
• Measuring cups
• Plastic zipper bag (large AND small size)
• Sodium chloride (salt)
• Rubbing alcohol
• Wooden toothpick/skewer
• Two bowls
• Liquid soap/shampoo
• Two CLEAR plastic cups
• Strawberries/banana
• Fork
• Few pieces of paper towel
• Scissors
Procedure
• Put your safety goggles on.
• Make an ice bath with one of the bowls, some water and the rubbing alcohol. Set the bottle of rubbing alcohol in here and allow it to chill.
• Place about six strawberries or half a banana in one of the bowls and mash it up REALLY well with the fork.
• Measure 125 mL (1/2 cup) of WARM water and add five mL (one teaspoon) of liquid soap to the water.
• Add the smashed up fruit to this mixture and stir it well.
• Allow this mixture to sit for about five minutes on the counter.
• Make another ice bath. Add the fruit /soap mixture to this ice bath and allow it to chill for five minutes.
• Snip one corner off of the plastic bag. Take one of the plastic cups and place the small plastic bag in it. Line the top of the bag with a few paper towels.
• Carefully pour the mixture over the paper towels and into the plastic bag. Go slowly as you want the mixture to filter through the paper towels.
• Once the mixture has filtered through the filters you should have a clear liquid in the bottom. Remove the bag and discard.
• Add one mL (1/4 teaspoon) of salt and stir well.
• Measure how much liquid you have with the measuring cups and pour it back into a clear glass. Add this amount of rubbing alcohol to your mixture now. I like to GENTLY pour it down the side of the clear glass.
• Allow this to sit for a minute and observe.
• You should see the mixture separating.
• Take the wooden toothpick and twist it around in this cloudy mixture.
• Remove and observe.
• This is fruit DNA!
What is going on?
I know this was a long experiment but how exciting to be able to see DNA. By breaking down the cell walls in the fruit we mashed it up. In order to separate out these cells, we had to use the detergent. We did not want it to go too far and had to stop this mixture from breaking down any further chilling it in the ice bath. By adding the salt and rubbing alcohol the DNA was allowed to break apart from the rest of the solution and float for the top for us to easily extract! This is always one of my favorite experiments and I hope you enjoyed it to!
Do not forget about our Science Challenge each and every week in February! Some great prizes to be won. Visit the Science Fair website @ seabsciencefair.ca for all the details.
Patty Rooks, Senior Scientific Consultant PRAXIS, “Connecting Science To The Community”. Contact Praxis at praxis@praxismh.ca, www. praxismh.ca, Tweet or follow us @PraxisMedHat, or friend us on Facebook. Address: #12 826 11 Street S. E., Medicine Hat, Alberta, T1A 1T7 Phone: 403.527.5365, email: praxis@ praxismh.ca.