Academic journal article The American Biology Teacher

Assessment of an ELISA Laboratory Exercise

Academic journal article The American Biology Teacher

Assessment of an ELISA Laboratory Exercise

Article excerpt

Immunology is one of the most important fields of study in biology, but it is also one of the most complicated because of the intricate biochemical and cellular mechanisms involved. Immunological probes (antibodies, antigens) provide important tools for scientists studying cell and molecular biology, as well as genetics and microbiology. Students at all educational levels, therefore, need to be aware of the immunological process and the various tools and techniques that immunology provides. A wide array of educational approaches have been developed to teach students about the different aspects of immunology, including wet-lab exercises (Brokaw & Cobb, 2009), semester-long inquiries (Goyette & DeLuca, 2007), dry-lab simulations (Baker & Moore, 1996), interactive "virtual" exercises accessed via computer (Howard Hughes Medical Institute, 2004), and educational videos (DnaTube.com, 2007).

One of the most widespread research tools using immunology is the enzyme-linked immunosorbent assay (ELISA), a technique developed in the early 1970s that allows for quantitative detection of small amounts of almost any molecule with antigenic properties (Engvall & Perlmann, 1971; Engvall, 2010). To illustrate the growing importance of the ELISA technique, a literature search in PubMed (National Library of Medicine) for the years 2006-2010 yielded almost 48,000 research articles that used the term "ELISA." This continues the sharply upward trend noted by Lequin (2005), showing that the use of this technique is rapidly expanding. ELISAs are used in myriad ways in diverse fields like biotechnology, medicine, agriculture, and environmental science. For example, home testing kits for detecting pregnancy are based on detecting the levels of the hormone human chorionic gonadotropin in women's urine using an ELISA-like chromatographic immunoassay (Cole et al., 2005). ELISAs are used in developing countries to identify pregnant women infected with HIV (Humphrey et al., 2010) and to detect contamination of soil by dioxin (Trindade et al., 2008).

Instructors generally recognize that incorporation of hands-on activities enriches student learning (Hofstein and Lunetta, 2004). Rather than prepare ELISA exercises from scratch (e.g., Russo et al., 1984; Anderson & McNellis, 1998; Brokaw & Cobb, 2009), many biology instructors are now purchasing commercially prepared ELISA kits offered by science-education companies. These kits are fairly complete, providing most of the required reagents along with instructor directions and student manual, thus providing reliability, lower cost, and instructional ease. Commercially available ELISA kits that utilize real antigens and antibodies are sold by Ward's Natural Science (Rochester, NY), Modern Biology (Lafayette, IN), and Bio-Rad Laboratories (Hercules, CA), among others. Companies like Carolina Biological Supply Company (Burlington, NC) and Flinn Scientific (Batavia, IL) offer inexpensive classroom kits that simulate ELISAs but don't actually use antigens or antibodies.

There have also been numerous publications to help instructors generate their own hands-on ELISA experiments for students (Russo et al., 1984; Anderson & McNellis, 1998; Grimes et al., 1998; Gerbig et al., 2000; Chow & Phoon, 2003; Preszler & Marion, 2006). These authors generally focused on the technical and pedagogical aspects of the ELISA technique and presented no substantial assessment of student learning. Haussmann et al. (2007) and Brokaw & Cobb (2009) included evaluations of student learning and success with their classroom ELISA exercises, but they were subjective. Goyette & DeLuca (2007) designed a semester-long lab-research project on immunology that centered on enzyme immunoassays and assessed student learning by monitoring student grades, laboratory reports, and student responses on year-end course evaluations. They reported that students learned more after carrying out student-directed research than when they completed instructor-designed experiments. …

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