Teaching the Principles That Govern the Structure & Function of Biomolecules

Abstract

All living organisms contain a common set of chemical compounds that range in size from simple ions containing a single element to large macromolecules composed of thousands of atoms covalently bonded together. General biology textbooks for high school or college students usually contain a long chapter that introduces students to the biochemistry of proteins, nucleic acids, carbohydrates, and lipids. This chapter is filled with diagrams showing the structures of the 20 amino acids found in proteins, the five purine and pyrimidine nucleotides that occur in DNA and RNA, some of the monosaccharides found in oligosaccharides and polysaccharides, and several examples of lipids. This introductory chapter may also include a discussion of the secondary, tertiary, and quaternary structures of proteins; the B and Z forms of DNA; the sheetlike structure of cellulose; and the organization of phospholipids in biological membranes. Many students have difficulty understanding this material, and so more advanced textbooks in biochemistry, cell biology, microbiology and physiology often contain chapters that repeat much of the same information. In teaching a large course in general microbiology, I have found that even if students have memorized the structures of some biologically important molecules, they have little understanding of the basic principles that govern their structure and function. Accordingly, I have tried to develop these principles more explicitly and to focus on general concepts rather than rote memorization. In this article, I describe four principles essential to understanding the properties of biological molecules. I then suggest some pedogogical strategies for teaching these principles using examples from my own area. While other teachers might use other strategies or examples, the principles I describe are quite general. By taking a more conceptual approach, I have found student mastery of this material can be increased dramatically.