LESSON PLAN: MOLECULES OF LIFE

 

Subject Area

  Characteristics of Living Things
Age or Grade

  10th/11th grade Biology
Estimated Length

  2 class blocks (~2.5 hr) 
Prerequisite knowledge/skills

  Students should know the basic characteristics of all living things and that living matter are composed of a few common basic elements - CHNOPS.
Description of New Content

  Structure and function of basic biomolecules
  - Carbohydrates, Proteins, Lipids and Nucleic acids.
 Lab activity to teach students how to identify the above biomolecules in everyday foods.
Goals
  • Students should be able to define and give examples of organic molecules 
  • Students should be aware of the structure and function of the four classes of organic molecules.
  • Students should be able to distinguish between various molecules using simple chemical tests.
  • Students should understand that foods have different nutritional content and appreciate the importance of a balanced diet.
Materials Needed


  Different foods (e.g., milk, honey, soda, cooking oil,chicken broth, etc.), Biuret's solution, Benedict's solution, Iodine, Sudan III stain, brown paper bags, beakers, test tubes, droppers, hot plate 

Procedure

 

 

 

 Opener
 Do now - students read chapter on 'Chemistry of Life' using SQ3R method for 5-10 minutes. Teacher and students discuss SQ3R responses for 5-10 minutes. Teacher should use this opportunity to highlight everyday examples of carbohydrates, proteins, lipids and nucleic acids.

Development
a. Lab activity - Use simple tests to determine the presence of various organic molecules in everyday foods.  Teachers do a pre-lab demo showing the 4 tests for starch, simple sugars, lipids and protein. Students should be clear on what to expect for a positive and negative test results before proceeding. Each group of 3-4 students will test 5 different foods for the different molecules and write down their observations.  
b. Post-lab exercise - discuss nutrition, health and digestion. Emphasize the need for a balanced diet because of the need for each of these molecules in our body. 

Closure
Class activity - Each student is assigned a word related to the organic molecules (e.g., hydrophobic, starch, glycosidic bond etc.) and create a colorful poster with a definition, illustration and example for the word.
Evaluation

  Students will be evaluated on their ability to perform relevant food tests on unlabeled test tubes and correctly identify the molecular components in each.
 Students' posters will be assessed for content, accuracy and creativity, and the best ones displayed in the classroom. Students will also be given a quiz to assess their understanding of the material.
Extensions

  Relate to the real world: Students research and write a  2-3 page report on specialized macromolecules (e.g., chitin, cellulose, etc.) and their specific functions within a living organism.
References SQ3R reading method: http://www.collegeboard.com/student/plan/college-success/26666.html
Contemporary Biology: Exploring the Science of Life (Textbook)