https://phet.colorado.edu/en/simulations/membrane-channels
Lab Overview
Semi-Permeable Membranes
This lab uses the PhET Membrane Channels simulation to help students explore the concept of semi-permeable membranes and how they control the movement of molecules across cell membranes. Students can manipulate different channels to observe how ions and molecules pass through membranes selectively, gaining an understanding of cellular transport mechanisms, including facilitated diffusion and active transport.
Learning Objectives
Aligned with the Victorian Curriculum, students will:
- VCSSU123: Explain how cells maintain homeostasis by controlling the movement of substances across membranes.
- VCSSU122: Understand how cellular activities are influenced by membrane structure and function.
By the end of this lab, students should be able to:
- Describe how semi-permeable membranes regulate the movement of substances in and out of cells.
- Differentiate between types of membrane transport (e.g., passive vs. active transport).
- Explain the roles of protein channels and carriers in facilitating molecule movement across membranes.
ACARA Digital Literacy Capabilities
- Locate information: Using simulation data to understand transport mechanisms.
- Manage digital data: Storing and retrieving information from digital platforms securely.
Lab Instructions
- Access the Simulation: PhET Membrane Channels Simulation.
- Explore Passive Transport:
- Observe how molecules move through channels based on concentration gradients, with no energy required.
- Adjust the concentration of ions on each side of the membrane and note the direction of movement.
- Experiment with Active Transport:
- Activate channels that use energy to transport molecules against their concentration gradient.
- Observe how ATP is used to move molecules across the membrane, even when they move from low to high concentration.
- Compare Different Channels:
- Experiment with different channel types, such as ion channels and gated channels, to see how selective transport occurs.
Assessment Questions
- Describe the role of semi-permeable membranes in regulating cellular homeostasis.
- Explain the difference between passive and active transport, providing examples of each from the simulation.
- How does the concentration gradient affect the movement of molecules across a membrane?
- Describe a real-life example of how cells use membrane channels to maintain internal balance.
Teacher Notes
Integrating with Lessons:
- This lab complements units on cell biology and physiology, offering a visual and interactive way to understand membrane structure and function.
- Encourage students to connect these concepts to physiological processes, such as nerve signaling and muscle contraction.
Common Misconceptions:
- Students may confuse passive transport with active transport; clarify that passive transport does not require energy, while active transport does.
- Reinforce that only specific molecules can pass through certain channels, based on size, charge, or other properties.
Extension Activities:
- Challenge students to model osmosis using the simulation by adjusting solute concentrations on either side of the membrane.
- Have students investigate the effects of mutations in channel proteins, relating these to conditions like cystic fibrosis.
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