Name:_____________________
Skittle/Peanut M&M Pump
Materials:
2 popsicle stick fences
1 paper mache box
1 clear plastic ball
20 skittles and 20 peanut M&Ms
3 small paper clips (same color)
1 big paper clip
1 oval wooden frame
(optional)
Activity:
We need your help! A very important cell that is vital to the survival of mankind
has broken down. We have discovered that a mechanism called the sodium
potassium pump is not working properly. Your mission, if you choose to accept it
is to be shrunk down to the microscopic level and infiltrate the cell. Once inside
the cell, you and your partner must manually activate the pump. You are our last
hope and the fate of mankind is in your hands! This message will self-destruct in 5
seconds…….
Procedure:
1) Facing your partner, set up your plasma membrane model so it is on the desk
2)
3)
4)
5)
in front of each of you. Assign one partner to sit inside the cell and the other
to sit outside the cell.
*Be clear on who is sitting where. Labels such as “In” and “Out” are
recommended
If you are sitting inside the cell take 16 M&Ms and 6 skittles and place them
on your side of the membrane. If you are sitting outside the cell take 14
skittles and 4 M&Ms and place them on your side of the membrane.
Now you are ready to work the pump! First, we begin with the person sitting
inside the cell. He/she is to pick up 3 skittles which represent 3 sodium ions,
and place them inside the pump.
Now that the pump is filled with sodium, the pump needs energy in order to
release the ions outside of the cell. This energy comes from Adenosine Triphosphate (ATP). The person who is sitting inside the cell should pick up an
ATP (paper clip chain) and attach it to the pump.
Once the ATP is attached, only one phosphate group should remain attached
to the pump. This means the rest of the molecule should become ADP and
be set aside.
* At this point, the pump should have 3 Sodium molecules inside, and
also have a phosphate group attached (1 small paperclip).
6) The person sitting outside the cell can now open the pump and remove the
sodium ions. Once the sodium ions are outside the cell, they can be replaced
with 2 peanut M&Ms which represent potassium ions.
7) The person sitting inside the cell will then remove the potassium ions from
the pump, and release them inside the cell. Also they need to remove the
phosphate from the pump.
8) Repeat the process until you know the steps by heart. Also be sure to switch
positions, so each partner has a chance to be inside the cell.
Questions:
1) How does active transport differ from diffusion, facilitated diffusion, and
osmosis?
2) Explain what a concentration gradient is, and why it is important in respect
to the sodium potassium pump? How was a gradient shown in the activity?
3) How could you rearrange your model/candy in order to demonstrate passive
transport?
4) What type of macromolecule forms the sodium/potassium pump? Where
does the energy come from to power this pump?
5) What characteristics of the plasma membrane make the sodium potassium
pump a necessity for cells to function properly?