Phospholipids Between Us: (Part 2) Transport Through Cell Membranes - Preview

Phospholipids Between Us: (Part 2) Transport Through Cell Membranes

Subject: Biology
Time: 2-3 class periods
Level: All high school levels of biology


The activity focuses on student understanding of the biology concept of passive diffusion. Each activity is divided into three main CT activities: 1) recording observations and gathering data and 2) analyzing data and 3) testing different simulation scenarios to understand a problem.

Lesson Plan developed by Kai Orton, PhD and Apurva Naik, PhD (Northwestern University) and based on the PhET Interactive Simulation: Membrane Channels (http://phet.colorado.edu/en/simulation/membrane-channels)

Learner Objectives:

1.     Students will understand how the cell membrane regulates what comes in and out of the cell.

2.     Students will understand the process of passive diffusion and facilitated transport and how/when molecules and particles will move through a membrane and when they will not.

3.     Students will be able to predict rates of diffusion and ion transport based on the number of protein channels present.

4.     Students will understand the differences between passive and selective diffusion and facilitated transport through a cell membrane.


Materials and Tools

Computer Systems Requirements:



Microsoft Windows 
Sun Java 1.5.0_15 or later

OS 10.5 or later 
Sun Java 1.5.0_19 or later


1.Students will use a PhET Interactive Simulation: Membrane Channels (http://phet.colorado.edu/en/simulation/membrane-channels)

2.In the simulation, students will drag the channels onto the membrane and then investigate what happens to molecules/particles.

3.The concentrations graphs are meant to give students qualitative, relative information to help them understand diffusion.



Begin the lesson by reviewing the differences between the cell wall and cell membrane, which can easily be confused by students. This is also an important topic because these two structures are very important to diffusion and osmosis.  Ask questions such as, “What is the difference between the cell wall and cell membrane?”

Explain how the cell wall is the outside lining of the cell that helps support cell structure and holds the cell together.  For plant cells the cell membrane lies within the cell wall, while it is the outer structure for animal cells. 

The cell membrane has the quality of being semi-permeable so it can allow various substances to go in and out of the cell.  A great example of a very simple cell everyone is familiar with is an egg, one of the largest cells. The shell is the cell wall and the thin lining we sometimes peel off the shell is the cell membrane. The white of the egg (clear runny part) is the cytoplasm and the yolk or yellow part is the nucleus. Plants have both a cell wall and a cell membrane. Animal cells usually do not have a cell wall.  Bird eggs are an exception.

After they have a firm understanding of this topic you can move on to the concept of diffusion and equilibrium. Next, discuss the topic of osmosis and how these two topics relate to one another.

There are data tables and graph paper attached as documents to this lesson


Setting up the simulation:

Open the “Membrane Channels” interactive simulation on the computer:

  1. Type http://phet.colorado.edu/en/simulations into the Internet browser.

  2. Click “Run Now” (bright green icon)


  1. Students should understand concepts of the cell and organelle function

  2. Student should have a clear understanding of the differences between a cell wall and cell membrane

  3. Students should be familiar with concepts like concentration, equilibrium and diffusion.

  4. Students should have already studied concepts in osmosis like tonicity and osmotic pressure.

Compatible With




chrome books




Next Generation Science Standards
  • Life Science
    • [HS-LS1] From Molecules to Organisms: Structures and Processes

Computational Thinking in STEM
  • Modeling and Simulation Practices
    • Using Computational Models to Find and Test Solutions
    • Using Computational Models to Understand a Concept
  • Computational Problem Solving Practices
    • Assessing Different Approaches/Solutions to a Problem
  • Data Practices
    • Analyzing Data
    • Collecting Data
    • Creating Data
    • Visualizing Data
  • Systems Thinking Practices
    • Understanding the Relationships within a System

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