An Inquiry-Based Introduction to Molecular Biology

Abstract

AN attraction of genetics instruction has traditionally been in its inquiry-based approach. More recently, the emphasis in genetics research and instruction has undergone a transition from examination of phenotypes to analyses of the macromolecules important for encoding (DNA) and decoding (RNA) information and regulation of information processing. With the incorporation of handson molecular biology into both secondary school and introductory level undergraduate curricula, the fascination with technology need not replace the inquiry-based approach long associated with genetics. Many students are currently introduced to molecular biology by running gels that allow them to ‘‘see’’ DNA. A demonstration of the technique of electrophoretic separation often takes precedence over the process of posing and answering questions using scientific reasoning. Kits are sold that include the hardware and reagents for running DNA gels and many include restriction endonucleases for fragmenting DNA. But, in the most common introductory molecular exercises, students ‘‘look’’ at uncut and cut DNA, and possibly measure fragment sizes, activities that are essentially observational, descriptive and intellectually passive for the students. The purpose of this report is to show that molecular biology, even in an introductory experience, can be presented in a more scientific framework. In fact, more can be done with less, in a more investigative setting! To highlight investigative approaches, two themes will be emphasized: a deductive determination of the nature of the nucleic acids visualized in a gel, and a comparison of different genomes. Why should students be asked to ‘‘take it on faith’’ that what they view on a gel is DNA? With the use of simple DNA preparations to isolate total nucleic acids and inexpensive nucleases, students can examine and distinguish both DNA and RNA. A simple, inexpensive two-hour DNA mini-prep using higher plant material will provide high-quality DNA, preserve the various RNAs in usable form, and will not be destructive to the organism (Murray & Thompson 1980). The