Hey. It's Mr. Andersen and I'm going to walk you through the steps of the
cellular respiration video or lab in this video. So step one. Obtain three vials with
steel washers on the bottom. So that's what these things are. I'm next going to put those
to the side. To save you a little bit of time I also have three little bits of paper towel.
And we'll use those in just a second. So I've just kind of ripped those out. Okay. So next
we're going to fill a 100 milliliter graduated cylinder with approximately 50 ml of water.
So I'm going to fill up 50 ml of water in here. Okay. Next thing I'm going to do is
I'm going to add 15 germinating peas. The germinating peas will be in a beaker. And
they're going to be swollen because they've been sitting in there over night. So I'm going
to put 15 of those in the graduated cylinder and measure the volume of that. So dropped
one. Okay. So it started at 50 ml and now it's at 57 ml. And so you may want to write
this down. Or you could just remember it. So I roughly have 7ml of germinating peas.
Those are going to be the biggest things. So you want to make sure that you always have
7 ml of each of everything. So I'm going to dump the water back out. And then I'm going
to put those 15 germinating peas on one of my paper towels. Next thing I'm going to do
is I'm going to get the same amount of glass beads. And so I'm going to pour in 50 ml again.
And now I'm going to pour in glass beads until I have 7 ml of that as well. There we go.
So now I've got 7 ml of glass beads. So let me dump the water out. And those go on one
of my paper towels. And then the last thing I want is non germinating peas. And so I'm
going to do that same thing again. I'm going to get 50 ml of water. Now I'm going to get
the non-germinating peas. Those are going to be much smaller. So now I'm going to add
15 of those. 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15. Okay. So that's only brought
my volume up to about 3 ml. And since I have to have 7 ml in everything, I'm going to add
glass beads until we bring that total up to 7. There we go. Okay. So now I'm going to
dump that out. I'm going to put this on the last paper towel over here. So I've got, oh
I dropped one. So again on my paper towels I've got 15 geminating peas. Glass beads of
the same volume. And then 15 of the non-germinating and glass beads. So the volume stays the same.
So now I can take that graduated and the germinating peas and the glass beads and get that out
of my way. Next thing I have to do is actually make my respirometer. And so to make a respirometer,
I've got these three vials. I'm going to add one of the, I'm going to grab one these cotton
balls. This is absorbent. Soft and absorbent. And so what you do is you take one of the
cotton balls. And so we want to make sure we have about the same volume in each. I'm
going to rip that into 3 equal little bits of cotton. There we go. And I'm just going
to stuff that down into the bottom of the respirometer. Now the pipette you can use
to push stuff down. Okay. So now we've got absorbent cotton on the bottom. Absorbent
means it soaks up liquid. Next thing we're going to do is we're going to put some potassium
hydroxide in the bottom. Potassium hydroxide remember grabs on to the carbon dioxide. And
turns it into a solid. This stuff is really really nasty. So you want to be really careful.
It's a poison. Make sure that you're not getting it in your eyes. Make sure you're not getting
it on your hands. So I'm going to take in 500 micro liters and I'm going to put it in
the absorbent cotton in the bottom. There we go. And seal that back up. Okay. Next thing
I want to do is I want to make sure that the peas aren't actually effected by that. So
on top of it we're going to put non absorbent cotton. It comes in the other bag. It's made
out of polyester. So I'm going to take about an equal amount. I'm going to put that on
top of the absorbent. And we're going to have about the same amount of each. And then I'm
going to push this down to the bottom. So now that liquid can't actually get up. That
potassium hydroxide can't get up to where the peas are. Okay. Next thing I want to do
is actually fill them up. And so one of them I'm going to put germinating peas. So there's
15 germinating peas in this one. I'm going to put the pipette on the top and I'm going
to seal it. So that we don't push it too hard, you could break the glass, but I want to make
sure that there is a tight seal. Let me grab a couple of more. Next one I'm going to put
just glass beads in. Now the reason we put glass beads in is that there maybe changes
just due to temperature changes. And we know that glass beads don't respire. And so if
there are any changes in the glass beads we can use that as a correction. Again I'm going
to put a seal in that. And then in the last one we're going to put non-germinating peas.
And then the beads so that we make sure that we have the same exact volume in each of those.
There we go. Okay. So now I'm going to seal that one up. This you can see that that one
went down a little bit farther. So I'm going to get a different pipette. Want to make sure
that all the pipettes match. There we go. So we have roughly the same volume on top
of each of those. Okay. Next thing we're actually going to measure respiration. So to do that
we're going to get one of these big tubs. And we're going to fill it up with water.
Water that's at room temperature. So we're going to fill it up with water that's room
temperature. Once you have that water in there we don't want to touch it. We don't want to
put our hands in there. We just want to let it sit. So that the temperature stays exactly
the same through out the experiment. Next thing is really important. It's called the
equilibration period. So what you're going to do is you're going to take you're three
respirometers. You're going to put them under water. But you're going to have it so the
end like this, is actually going to come out. So they're going to be under water. The respirometers.
And then we're going to have the pipettes come out the side. And we want to let it sit
there for about 10 minutes so it can actually equilibrate to the temperature. So we want
the temperature inside the respirometers to be the same as the temperature in the water.
So after it's done that, we'll then take our respirometers and we'll put the flat down
in the water. Sometime you'll have to put something on top of them to hold it there.
So you can use a beaker. You could actually use a beaker, take some water and put it on
top of them to make sure that they stay down. You then just let it sit there until you can
actually see measurements inside the pipette. Once you can see measurements inside the pipette
then you're ready to go. So you're just going to start your watch and record the initial
amount in each of the pipettes, remembering which one is germinating, glass beads and
non-germinating and glass beads. You'll then record it at time 0. And then you're going
to record it at 5, 10, 15, and 20 minutes. You can then use the glass beads to correct
for changes just due to environment. But what we should see is changes. In other words as
the organisms that happen to be doing respiration are consuming oxygen, they're producing carbon
dioxide. Carbon dioxide is grabbed by the potassium hydroxide. So it's eliminated. so
we should see the water start to flow in the pipette. So we can measure the respirometer.
The only trick to that is actually measuring the pipettes. The delineations on the pipettes
are really really small. Just to wrap your head around it, this would be, right here
from 0 to 1 is 1 milliliter. And so we're actually measuring hundredths of milliliters.
So this is going to be very very small. You may want to take a look at the pipettes before
you actually put them under water. Because once it's under water it's kind of hard to
measure it. So that's the cellular respiration lab. And I hope that's helpful.