Science Mom Extracts DNA from a Strawberry


This is a strawberry. Cut it in half, and you
have half a strawberry. Break it down into
smaller and smaller pieces and eventually you’ll get
down to a piece so small, it’s called a single-cell. This microscopic unit
is the building block of all living things. I’m made of cells
this desert tortoise is made up of cells and this big tree is
made up of cells too. So if a strawberry and a banana are both made up of cells why do they look
so different? Well, it’s because they have different DNA. DNA is like the
instructions for the cell. They tell it how to live and what to do. The DNA inside the strawberry tells the cells to produce a anthocyanin, the pigment that makes
them red and to make a lot of vitamin C. The DNA inside the banana tells it to
make a lot of vitamin B6 and starch and for that outer layer of cells to
differentiate and become harder and make the peel. Today I’m going to show you how
to take the DNA out of a strawberry using soap salt and rubbing alcohol. The first thing you want to do is really mash up your fruit. [music] One of the most common mistakes
people make when they do this is not squishing the strawberry
enough. You don’t want it to be chunky. You want to mix it until it’s completely
liquefied and smooth. Next we’re going to make our
extraction solution by getting a half cup of warm water and adding in
1 teaspoon of salt and 2 teaspoons of
concentrated dishsoap. and then mix that together well add two to three teaspoons of this to
your strawberry and mix again. The purpose of the soapy salty water is to
further break open the cells and to help the DNA come out from the nucleus and
the membranes and get into the liquid you don’t want to make it too soapy or
frothy but you do want to mix it well and spend several seconds squishing the
bag around. Then put a coffee filter over a jar or a cup so that it’s secure and it
won’t slip in, and pour in your strawberry mixture Wait for about five minutes for the
liquid to drip through. and then if you’d like, you can very carefully and
gently squeeze the coffee bag to get a little bit more liquid out. Be really
careful with this step that you don’t push too hard and break your bag
because then you’ll have to strain the whole thing through a coffee filter
all over again. There is tons of DNA from the strawberry inside the liquid here. The
only way we’ll be able to see it if we can get it to all clump together. We’re
going to precipitate our DNA. “Precipitate” means that all of the DNA is going to
come out of solution and clump together. To do this, we need rubbing alcohol. We’re
going to pour in about an equal amount to however much strawberry liquid that you
have. You want to pour on a layer that’s about similar thickness. Just let it sit
and you’ll start to see the DNA floating up into the rubbing alcohol. It looks
like a white bubbly cloudy layer. And now that you can see all that white bubbly
material collected together we’re ready to just dip a toothpick in and lift out
the DNA. Whoa! We got a lot this time so
there’s part of our DNA. I’ll try and get in and scoop out the rest. There we
go. That’s the strawberry DNA. If you put it in the bag and then press it out you
can see just how long and strand like the DNA is. DNA is incredibly long
molecule. In fact if you took one human cell and then stretched the DNA out flat
it would be [nearly] six feet long, which is just incredible, a little
mind-boggling to think about. But this long, long strand is so thin and small
and it’s coiled around itself so tightly that it fits inside a nucleus which is
just microscopic. When you put the DNA into the bag and then press it out, you
can see just how stringy it is because it is such a long polymer. And that’s
probably one of my favorite parts of this experiment and seeing
it in the bag and spreading it out and seeing how thread-like and filamentous
the DNA is. Don’t forget to check out the coloring pages worksheets and the other
two videos that go along with the science investigation. The worksheets are
free downloads and you can find a link to them in the description. This video is
made possible by the support of my patrons on Patreon. A big thank you to
all of my patrons for helping me do this, and a warm welcome to the newest member
of our Periodic Table of Patrons, a talented engineer who is represented by
the element Bachartanium. If you’d like to join us on patreon you can find
the link to that in this info card here, or down in the description or from my
website. Thank you again for watching.

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