Curricular Unit: Keepers of the Gate

Contributed by: VU Bioengineering RET Program, School of Engineering, Vanderbilt University

Cartoon of a microscope and cell culture.
The cell and Its gatekeeper, the cell membrane.
Copyright © 2004 Microsoft Corporation, One Microsoft Way, Redmond, WA 98052-6399 USA.


Through two lessons and five activities, students explore the structure and function of cell membranes. Specific transport functions, including active and passive transport, are presented. In the legacy cycle tradition, students are motivated with a Grand Challenge question. As they study the ingress and egress of particles through membranes, students learn about quantum dots and biotechnology through the concept of intracellular engineering.

Engineering Connection

Engineers use nanoparticles, such as quantum dots, in biomedical engineering, bionanotechnology and cancer cell research. Students emulate intracellular engineers as they analyze authentic data and make predictions on cell lysis techniques based on their analyses. Experimental design is employed as a final project as students design protocols and carry out experiments that prove their answers to the challenge question.

More Curriculum Like This

Cell Membrane Structure and Function

Students learn about the different structures that comprise cell membranes, fulfilling part of the Research and Revise stages of the legacy cycle. They view online animations of cell membrane dynamics (links provided).

Active and Passive Transport: Red Rover Send Particles Over

Students compare and contrast passive and active transport by playing a game to model this phenomenon. Movement through cell membranes is also modeled, as well as the structure and movement typical of the fluid mosaic model of the cell membrane.

The Keepers of the Gate Challenge

Students are presented with a real-life problem as a challenge to investigate, research and solve. Specifically, they are asked to investigate why salt water helps a sore throat, and how engineers apply this understanding to solve other problems.

Tell Me the Odds (of Cancer)

Through four lessons and three hands-on activities, students learn the concepts of refraction and interference in order to solve an engineering challenge. Students learn about some high-tech materials and delve into the properties of light, including the equations of refraction (index of refraction,...

Educational Standards

Each TeachEngineering lesson or activity is correlated to one or more K-12 science, technology, engineering or math (STEM) educational standards.

All 100,000+ K-12 STEM standards covered in TeachEngineering are collected, maintained and packaged by the Achievement Standards Network (ASN), a project of D2L (

In the ASN, standards are hierarchically structured: first by source; e.g., by state; within source by type; e.g., science or mathematics; within type by subtype, then by grade, etc.

  • Research and development is a specific problem-solving approach that is used intensively in business and industry to prepare devices and systems for the marketplace. (Grades 9 - 12) Details... View more aligned curriculum... Do you agree with this alignment?
  • Technological problems must be researched before they can be solved. (Grades 9 - 12) Details... View more aligned curriculum... Do you agree with this alignment?
  • Identify the design problem to solve and decide whether or not to address it. (Grades 9 - 12) Details... View more aligned curriculum... Do you agree with this alignment?
  • Identify criteria and constraints and determine how these will affect the design process. (Grades 9 - 12) Details... View more aligned curriculum... Do you agree with this alignment?
  • Refine a design by using prototypes and modeling to ensure quality, efficiency, and productivity of the final product. (Grades 9 - 12) Details... View more aligned curriculum... Do you agree with this alignment?
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Unit Overview

This "legacy cycle" unit is structured with a contextually-based Grand Challenge followed by a sequence of instruction in which students first offer initial predictions (Generate Ideas) and then gather information from multiple sources (Multiple Perspectives). This is followed by Research and Revise, as students integrate and extend their knowledge through a variety of learning activities. The cycle concludes with formative (Test Your Mettle) and summative (Go Public) assessments that lead students towards answering the Challenge question. See below for the progression of the legacy cycle through the unit and the suggested order to conduct the lessons and activities. Research and ideas behind this way of learning may be found in How People Learn (Bransford, Brown & Cocking, National Academy Press, 2000; see the entire text at

The "legacy cycle" is similar to the "engineering design process" in that they both involve identifying an existing societal need, applying science and math concepts to develop solutions, and using the research conclusions to design a clear, conceived solution to the original challenge. Though the engineering design process and the legacy cycle depend on correct and accurate solutions, each focuses particularly on how the solution is devised and presented. See an overview of the engineering design process at

In lesson 1, "The Keepers of the Gate Challenge," students are presented with the Grand Challenge question: "You are spending the night with your grandmother when your throat starts to feel sore. Your grandma tells you to gargle with salt water and it will feel much better. Thinking this is an old-wives tale, you scoff, but when you try it later that night it works! Why?" From this, they brainstorm to Generate Ideas. As part of the Multiple Perspectives stage, students listen to an audio or video of Dr. Z. L. Wang as he discusses the value of nanotechnology. Students also review an article pertaining to cancer cells illuminated with quantum dots. During this lesson's associated activity (activity 1), "Keepers of the Gate Journal and Brainstorm," students document their thoughts and responses to the questions from the Generate Ideas stage. Questions include "What are your initial ideas about how this question can be answered? What background knowledge is needed? Have you tried this before?" After this, the class brainstorms to reach consensus on the main ideas that need to be explored in the unit.

In lesson 2, as part of the Research and Revise, students learn about the different structures that comprise the cell membrane. They also relate cell membrane structure with function. One of the best ways to learn about a dynamic model is to view animations. A resource document provides many animations for students to choose from for analysis. After students view animations of cell membrane dynamics online, they observe teacher demonstrations of diffusion and osmosis. Students also witness the effect of movement through a semi-permeable membrane using Lugol's solution.

In the lesson's associated activity (activity 2), "Cell Membrane Color Sheet and Build a Cell Membrane," students color in the outline of structures on a cell membrane color sheet. Another optional activity for lesson 2 is the "Build-a-Membrane" activity found at Both activities begin the Test Your Mettle phase with a formative assessment for the cell membrane. Students check their understanding of the basic cell membrane structure and the function of each part.

Activity 3, "Active and Passive Transport: Red Rover Send Particles Over," introduces students to the transport of particles into and out of the cell. Transport (both active and passive) is the emphasis for Research and Revise phase. The teacher briefly lectures on active and passive transport to help students define transport and compare and contrast different types of particle transport across a cell membrane. Transport happens across a cell membrane to maintain homeostasis. Two main types of transport exist: passive and active. Passive transport is the movement of substances across the membrane without any input of energy from the cell. Active transport refers to movement of materials from an area of lower concentration to an area of higher concentration (against the concentration gradient). Energy is needed, usually from ATP. Then, students play Red Rover-Send Particles Over—a cell membrane game. Through this kinesthetic learning, students explore relationships within the cell involving the cell membrane. Finally, the students also take a quiz to assess their understanding of the material.

Through the Research and Revise and Test Your Mettle phases in activity 4, "Quantum Dots and the Harkness Method," students learn about quantum dots and how they are used in bionanotechnology and cancer cell research. They explore how cell biotechnology research relates to cell membranes. Students read and discuss a professional journal article, using provided "Harkness framing questions" (article: THe "Harkness-method" of discussion helps students become critical readers of scientific literature.

During the final activity (activity 5), "Cell Membrane Experimental Design," which integrates the entire unit through the Go Public phase, students take part in experimental design. They design labs that answer the challenge question. Students must have their plans approved by the instructor before beginning. A formal lab write-up is required as part of the laboratory investigation. Students connect the importance of designing an experiment to the engineering design process; they discuss how experimental design helps further the understanding of a naturally occurring phenomenon, which allows engineers to design better solutions to defined problems.

Unit Schedule

Day 1

  • Lesson 1 - Keepers of the Gate Challenge
  • Activity 1 - Keepers of the Gate Journal and Brainstorm
  • Lesson 2 - Cell Membrane Structure and Function
  • Activity 2 - Cell Membrane Color Sheet and Build a Cell Membrane

Day 2

  • Activity 3 - Active and Passive Transport: Red Rover Send Particles Over
  • Homework for Day 2 - read the journal article

Day 3

  • Activity 4 - Quantum Dots Journal Reading and Harkness Framing Questions
  • Homework for Day 3 - reflect on experimental proposals

Day 4

  • Activity 5- Cell Membrane Experimental Design
  • Homework for Day 4 - write lab report

Day 5

Summary Assessment: Students write their final reflections and answer the challenge question with a one-page paper that includes their conclusions and supporting evidence.


Melinda M. Higgins


© 2013 by Regents of the University of Colorado; original © 2010 Vanderbilt University

Supporting Program

VU Bioengineering RET Program, School of Engineering, Vanderbilt University


The contents of this digital library curriculum were developed under National Science Foundation RET grants no. 0338092 and 0742871. However, these contents do not necessarily represent the policies of the NSF, and you should not assume endorsement by the federal government.

Last modified: July 20, 2017