Chem Connections


Cholesterol: Structure and Function in the Human Body

Cholesterol Image


holesterol

Prerequisites:
Particulate Nature of Matter (atoms and molecules)
Atomic Structure and Periodic Properties (orbitals, electron configurations)
Structure and Bonding (covalent bonding, lewis dot structures, formal charges, bonding theories)
Energetics (free energy)
Interdisciplinary aspects: Biology
Classroom and laboratory: Both
Number of one hour class periods: 9-12
Number of 3-4 laboratory periods: 2-3

Roseann K. Sachs
Chemistry Department
Colorado College
14 E. Cache La Poudre
Colorado Springs, CO 80903
(719)389-6431
rsachs@cc.colorado.edu

Laura Parmentier
Department of Chemistry
Beloit College
700 College Street
Beloit, WI 53511
(608)363-2274
parmentr@beloit.edu

Description

This module will focus on the role of cholesterol in the human body. In recent years, the harmful role of cholesterol in the body has been widely publicized. However, cholesterol also has many useful functions in the body including its role in membrane structure, brain tissue, fetal development and the biosynthesis of other steroidal hormones. It is a subject that is intimately connected to the human body. Since many of the students we teach are ultimately interested in life science careers, I believe this topic will be of great interest to them. It also gives them a chance to better understand a subject that is discussed widely in the media and to give them a more in depth, scientific understanding of it.

We will begin by learning the structure of cholesterol, including its three-dimensional shape. In order to understand this fairly complicated molecule, we will begin by learning the structure of the carbon atom itself which should introduce the students to Lewis Structures as well as hybridization. Next we will have to examine the effect of putting so many carbon atoms together in a polycyclic system. Is the molecule rigid? Are there various conformations of the molecule and what would t heir relative energies be? This will allow us to explore conformational analysis in both acyclic and cyclic carbon systems. One can introduce thermochemistry, kinetics and free energy diagrams through this topic as well.

Finally we can extend this study to other steroids. A variety of other functional groups can be introduced in this way and the students will be able to gain a basic understanding of how functionality affects structure, as well as reactivity. Stereochemistry will also be taught at this point. In summary, the chemical principles that would be dealt with in this module include: Hybridization, shapes, isomers, polarity and stereochemistry); Conformational Analysis (acyclic compounds and cyclohexanes); and Introduction to Functional Groups.

Our pedagogical approach will be to have students construct their own understanding of the structure of cholesterol through discovery, in consultation with a standard organic textbook. This will be done through guided and open-ended in-class and out-of class activities. Both model kits and computer modeling will be used to understand the three-dimensional shape of cholesterol. Students might be assigned group projects in which their task would be to explain some function of cholesterol in the body, to introduce the class to a new functional group, or to summarize the activity of a different steroid in the body. The laboratory could involve such activities as isolating cholesterol, computer modeling, as well as other experiments that allow for the student to be involved in both experimental design and data analysis. In summary, the module will be derived from student-guided learning, involving significant amounts of communication skills, both oral and written.

Assessment of what the student has learned will include both individual and group examinations. It will most likely also include oral presentations, a poster presentation, work on daily assignments and skill in the laboratory.

Tool Kit
Chemical Principles:
Structure and Bonding in Organic Molecules (lewis dot structures, hybridization, shapes, isomers, polarity and stereochemistry)
Conformational Analysis (cyclohexanes)
Introduction to Functional Groups

Thinking Like A Scientist:
Laboratory Procedures (purification and synthesis)
Experimental Design (decision making and safety issues)
Accessing Information (computer/library searching, using reference books, evaluating the reliability of information)
Critical Thinking (recognizing trends, deduction, inference, independent and collaborative learning)
Communication (oral, written, visual, teamwork, lab notebook)

Audience: First semester organic students

Materials to be developed

Multimedia Materials

  • Classroom activities
  • Problem sets
  • Transparencies

Standard Materials

  • Short readings to accompany the traditional text
  • Additional reading for the instructor
  • Laboratories


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Last modified: 10/18/00 at 11:50 AM