Lesson Plan

Cell Transportation

Objectives

In this lesson, students compare the mechanisms (i.e., active and passive transport) that transport materials across the plasma membrane. Students will:

  • Differentiate between active transport and passive transport.
  • Compare the mechanisms of passive transport (i.e., diffusion, osmosis, facilitated diffusion) and active transport (i.e., pumps, endocytosis, and exocytosis).
  • Describe the role of ATP in active transport mechanisms.

Essential Questions

Vocabulary

  • Active Transport: Process that moves materials across the plasma membrane against a concentration gradient; requires energy.
  • Carrier Protein: Protein that transports materials into or out of the cell in active transport.
  • Concentration Gradient: When a solute in a cell is in high concentration on one side of a membrane compared to the other.
  • Diffusion: The movement of molecules across a membrane, with a net movement from high to low concentration.
  • Endocyctosis: When a cell actively takes material into itself by folding the plasma membrane inward, forming a vesicle.
  • Exocytosis: When a cell actively releases material by folding the plasma membrane outward, forming a vesicle.
  • Facilitated Diffusion: Passive movement of molecules across a plasma membrane through protein channels.
  • Fluid Mosaic Model: Model of the plasma membrane in which proteins are embedded in phospholipids.
  • Isotonic: Two solutions have equal concentrations of solutes.
  • Homeostasis: The process by which organisms maintain a stable internal environment.
  • Hypertonic: (hyper = above) When comparing two solutions, the solution with a greater concentration of solute.
  • Hypotonic: (hypo = under) When comparing two solutions, the solution with a lesser concentration of solute.
  • Osmosis: Diffusion of water through a selectively permeable membrane from an area of high concentration to an area of low concentration.
  • Passive Transport: Process that moves solutes down their concentration gradient across the plasma membrane; does not require energy.
  • Selective Permeability: Property of biological membranes that allows only certain substances to pass through them; the cell membrane and the membranes of organelles are selectively permeable.
  • Vesicles: Small membrane-bound spaces in the plasma membrane that transport macromolecules into and out of the cell.

Duration

90 minutes/2 class periods

Prerequisite Skills

Prerequisite Skills haven't been entered into the lesson plan.

Materials

Related Unit and Lesson Plans

Related Materials & Resources

The possible inclusion of commercial websites below is not an implied endorsement of their products, which are not free, and are not required for this lesson plan.

Formative Assessment

  • View
    • Collect and assess the Diffusion Lab worksheet and the Comparing Types of Transport across the Plasma Membrane chart.
    • Monitor students during the diffusion lab and ask questions to check for understanding.
    • Assess students during the warm-up and closing activities on Day 2.
    • Have students explain the diagram shown in Comparing Passive Transport and Active Transport (S-B-7-3_Comparing Passive Transport and Active Transport.doc).

Suggested Instructional Supports

  • View
    Active Engagement, Modeling, Explicit Instruction
    W: This lesson compares the active and passive transport mechanisms that transport materials across the plasma membrane.
    H: The lesson begins with an inquiry lab on diffusion to hook students’ interest in how cells transport materials and provide a real-world example of how selectively permeable membranes work.
    E: This lesson includes a lab activity, PowerPoint presentations, diagrams, online animations, and a graphic organizer on the types of active and passive transport.
    R: Students answer questions during and after the lab activity. They complete a chart that compares the types of active and passive transport, and define vocabulary terms in their own words.
    E: Students can express their understanding during the lab activity, on the chart, and in the warm-up and concluding exercises for Day 2.
    T: This lesson can be tailored by reviewing the vocabulary terms that are related to the various transport mechanisms, and by having students revisit and practice differentiating between the types of transport.
    O: The lesson begins with a discovery lab on diffusion to lead to students’ understanding that the plasma membrane is selectively permeable. Students learn about the structure and function of the plasma membrane, and then view PowerPoint presentations on active and passive transport mechanisms. Several online animations are suggested for more in-depth coverage of osmosis and the role of ATP.

Instructional Procedures

  • View

    Day 1: Passive Transport: Diffusion, Osmosis, Facilitated Diffusion

    Diffusion Lab

    Note: Dialysis tubing can be used to demonstrate diffusion instead of the plastic sandwich bags, following the procedure shown below:

    1. Obtain a piece of dialysis tubing. Tie a knot at one end then fill it 1/4 with water.

    2. Make sure the tube does not leak. Empty the water out of the tubing.

    3. Add 3 teaspoons of corn starch to the tubing.

    4. Squeeze the air out of the tubing. Tie a knot on the open end.

    5. Rinse off the tubing under running water.

    6. Fill a 250-mLbeaker 3/4 full with water. Add 10 to 15 drops of iodine and stir.

    7. Place a paper clip around each knot in the tube. Hang the tube in the beaker of water.

    This lab will help students understand about how diffusion works with a selectively permeable (or “semipermeable”) cell membrane. You may choose to have small groups of students do the lab, or you can set it up as a demonstration.

    Give students the Diffusion Lab worksheet (S-B-7-3_Diffusion Lab and KEY.doc). Read the introduction with students and define selectively permeable membrane. Follow the procedure to set up the lab activity, and have students answer the questions on the worksheet while they are waiting for about fifteen minutes. Then, have them observe the changes and answer the post-lab questions.

    Students may think that the iodine “ate through” the bag. Explain that the bag has tiny pores in it like a window screen and that iodine is a small molecule that can pass through the openings.

    Show students the Plasma Membrane Diagram (S-B-7-3_Plasma Membrane Diagram.doc). Explain that the plasma membrane is selectively permeable to allow only certain materials to pass in and out. Describe the parts of the plasma membrane and explain the functions of proteins as channels and pumps for transporting materials and carbohydrates as chemical identification tags for other cells. Explain that scientists today use the fluid mosaic model, a widely accepted model of the plasma membrane in which proteins are embedded in lipids.

    Instruction continues by handing out Comparing Types of Transport across the Plasma Membrane (S-B-7-3_Comparing Types of Transport and KEY.doc). Tell students to fill in the chart as you go through the PowerPoint on passive transport.

    Show students the Passive Transport PowerPoint (S-B-7-3_Passive Transport PPT.pptx). Make sure that they understand that passive transport does not require energy because it is the movement of materials in the direction of the concentration gradient.

    If time permits, show students an osmosis animation at www.stolaf.edu/people/giannini/flashanimat/transport/osmosis.swf. Before you press the “Add Salt” button, have students predict what will happen to the movement of water molecules.

    Day 2: Active Transport: Pumps, Endocytosis, Exocytosis

    Warm-up the lesson for today: “What is the role of ATP in photosynthesis and cell respiration?” (ATP stores energy in its chemical bonds. Photosynthesis produces ATP, and cell respiration uses the energy stored in ATP to break down glucose to release energy.)

    Use a projector to show students the interactive ATP and Energy Storage animation at http://biologyinmotion.com/atp/index.html. Read through the short tutorial about the role of ATP and then have students explain what is happening at each stage of the animation.

    Show students the Endocytosis and Exocytosis diagram (S-B-7-3_Endocytosis and Exocytosis.doc).

    Have students take out Comparing Types of Transport across the Plasma Membrane (S-B-7-3_Comparing Types of Transport and KEY.doc). Tell students to continue filling in the chart as you go through the PowerPoint on active transport.

    Show students the Active Transport PowerPoint (S-B-7-3_Active Transport PPT.pptx). Make sure that they understand that active transport requires energy from the cell because it is the movement of materials against the direction of the concentration gradient.

    Review the role of ATP (and ADP) in active transport.

    Define homeostasis as the process by which organisms maintain a stable internal environment. Have students write a sentence that explains the relationship between active transport and homeostasis. (Example: Cells take in or remove materials through active transport to keep a balance inside the cell.)

    Extension:

    • Students who might need an opportunity for additional learning can create a concept map that organizes the ways cells move materials in and out (active and passive transport mechanisms).
    • Students who might need an opportunity for additional learning can draw diagrams that symbolize each of the different types of passive and active transport.
    • Students who might need an opportunity for additional learning can view the animations for active and passive transport on the Web sites provided in the Related Resources section.
    • Students who might need an opportunity for additional learning can write a one-sentence summary for each type of active and passive transport.
    • Students who may be going beyond the standards can design and carry out an experiment to demonstrate how osmosis affects plant cells (e.g., placing plant cells on a wet mount slide in hypertonic and hypotonic solutions and observing the results).

Related Instructional Videos

Note: Video playback may not work on all devices.
Instructional videos haven't been assigned to the lesson plan.
DRAFT 05/26/2011
Loading
Please wait...