Cell Transport Activity
Using Lemon Heads and Smarties to illustrate passive
and active cell transport
Pre-step 1: Draw a cell membrane
and label the “nonpolar” region
Pre-step 2: Make a “key”
Step 1: Place all but three of your Smarties on
the OUTSIDE of your membrane
Step 2: Move the “nonpolar” Smarties through
the membrane to facilitate “simple diffusion”.
Why can’t the “polar” (purple) Smarties “simply
diffuse” through the membrane?
Because the inside of the membrane is “nonpolar” and
it does not allow “polar” molecules to pass through.
Step 2 continued: Can Large molecules “simply
diffuse” through the membrane?
No! Notice that the Lemon Heads (large
molecules) did not move because they do no fit.
Step 3: What if they had help?
Draw a membrane protein
Step 3 cont.: The large and polar molecules have
to get through the membrane somehow…
They are “facilitated” (helped) by a
membrane transport protein
This helps large (Lemon Heads) and polar
(purple Smarties) molecules cross the
nonpolar and small membrane.
Remember, the goal of cell transport is to reach
“equilibrium” so there is an equal number of
molecules on either side of the membrane.