Self-Assembly with Nanomanufacturing (a 9-page activity)

Interactive, scaffolded model

Overview and Learning Objectives

Students learn the necessary conditions for self-assembly (random motion and molecular stickiness), play with some example models of self-assembling biological structures (quartenary structures such as hemoglobin, fibers, and microtubules), and then design their own self-assembly structures.

Students will be able to:

• identify and manipulate two key characteristics of molecules that allow them to self-assemble;
• describe the effect of temperature on self-assembly;
• give examples of the effect of molecular shape on the larger structures built by self-assembly.

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Assessment

Download a pre- and post-assessment from:

http://www.concord.org/~barbara/workbench_web/pdf/selfassembly_assess.fin.pdf

http://www.concord.org/~barbara/workbench_web/pdf/selfassembly_RUBRIC2.pdf

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Classroom Practice

Self-assembly is not part of the traditional biology curriculum, but it is a powerful idea relating to many concepts that are. This activity can serve as an engaging introduction. With a teacher’s guidance, students should also be able to generalize from these simple examples to the formation of more complex molecular structures.

For example, after doing this activity, students might be interested in the story of the T4 phage, a virus with a beautiful self-assembling icosahedral capsid. The virus contains just a small amount of genetic material, which seems hardly enough to contain the instructions for building its complex, symmetrical shell, made of thousands of parts; it turns out that these parts are identical monomers that self-assemble.

Another interesting question for class discussion is whether or not everything biological is constructed through self-assembly. You can point out that chemical reactions catalyzed by enzymes are required to form the covalent bonds that hold many structures together. These bonds are much stronger than the charge attractions students see in the activity. You can also describe the role of template-based synthesis (making one nucleotide strand by copying it from another) and of chaperone molecules (which help proteins fold into the right shape by shielding them from the influence of surrounding water molecules).

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Central Concepts

Key Concept:

Self-assembly is the spontaneous formation of organized structures from smaller subunits. Both random motion and interparticle interactions are necessary for it to occur.

Additional Related Concepts

Concept Map Available

Molecular Biology

• Self-assembly

Physics/Chemistry

• Charge
• Molecular movement

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Textbook References

• Biology (Miller and Levine) Prentice Hall 5th Edition - Unit 2: Chapter 7 - Nucleic Acids and Protein Synthesis
• Biology: Concepts and Connections (Pearson) 5th Edition - Chapter 4: A Tour of the Cell
• Biology: Exploring Life - Chapter 5: The Molecules of Life
• BSCS Blue (8th Edition) - Chapter 23 - Immune System
• BSCS Blue (8th Edition) - Chapter 9: Expressing Genetic Information
• Cell Biology (Pollard and Earnshaw) Saunders 2002 - Chapter Four: Macromolecular AAssembly
• Cell Biology (Pollard and Earnshaw) Saunders 2002 - Chapter One: General Principles of Cellular Organization

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Benchmarks and Standards

AAAS

• THE LIVING ENVIRONMENT: CELLS - Most cells function best within a narrow range of temperature and acidity (Full Text of Standard)
  
  

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Extensions and Connections

This activity continues to explore ways in which proteins assume their shapes to provide structure and machinery for cells. This makes it a natural extension for the previous Stepping Stone Activity Protein Folding (http://molo.concord.org/database/activities/225.html).

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Activity Credits

Created by CC Project: Molecular Workbench using Molecular Workbench

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Requirements

• Java 1.5+ - Java 1.5+ is available for Windows, Linux, and Mac OS X 10.4 and greater. If you are using Mac OS X 10.3, you can download MW Version 1.3 and explore within it instead.

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