August 2002

The purpose of this article is to help teachers integrate biotechnology into their classroom, by providing resources along with background information and a guide to appropriate topics and exercises. Should biotechnology topics be included in the Biology classroom? My answer is a resounding “Yes!” because biotechnology

• can provide a “hook” for getting students interested in and excited about biology, since this topic is frequently featured in the news media

• illustrates the integration of basic scientific research into applied biology; for example, basic research about the biology of viruses that infect bacteria led to the modification of viral DNA to act as a vehicle for moving specific genes from one cell to another

• underlies many current social and ethical controversies

• encompasses methods that are widely used in all areas of biology, and students with an interest in biological research should be exposed to these techniques early in their training

In spite of the importance of biotechnology in modern biological science, many teachers are reluctant to include concepts about biotechnology in their classrooms because they are concerned that biotechnology

• may be too complex for students
• may be too expensive to implement
• is not within the teacher’s area of expertise
• may be too controversial to manage in the classroom

However, many resources are available to help teachers incorporate laboratory and other biotechnology activities in the classroom, to provide background, and to facilitate discussions about controversial topics.

Biotechnology techniques and background

Modern biotechnology methods rely on the isolation and subsequent manipulation of DNA. Once students are familiar with DNA and its role in genetics, a useful starting point for introducing biotechnology concepts is DNA isolation.

DNA isolation

Although DNA isolation techniques vary slightly depending on the experimental organism, all of these techniques share the following characteristics:

• a treatment for breaking open cells and releasing DNA
• a method for removing or inactivating DNA-degrading enzymes
• a means of separating DNA from proteins and other contaminating molecules

There are several simple, inexpensive laboratory exercises for DNA isolation from bacteria, onions, and other organisms. They generally use heat and detergent to break open cells and inactivate DNA-degrading enzymes, and separate DNA from most other contaminants using precipitation with alcohol. There are many published methods for simple DNA isolation. The method I have found to be most reproducible is DNA isolation from bacteria¹⁶, although there are a number of published isolation exercises using onions^9,10,12,16 and other organisms and tissues. Many biological supply companies sell kits for this technique and others.

DNA transformation

Another technique at the heart of many biotechnology methods, called DNA transformation, involves adding foreign DNA to cells. This foreign DNA then can be “turned on” to make a useful product. This method has been used to produce many pharmaceuticals, such as human insulin.

For classroom purposes, DNA transformation is most easily accomplished in bacteria. The basic scheme is to

• take a bacterial mini-chromosome called a plasmid,
• insert foreign DNA into the plasmid,
• and then put the modified plasmid back into bacteria.

Many transformation laboratory exercises have been published.^4,15,16 Some companies sell pre-packaged DNA transformation kits.

Restriction enzyme digestion and analysis

Restriction enzymes are proteins that cut DNA molecules at specific sequences of bases. These enzymes allow biotechnologists to reproducibly cut DNA molecules into well-defined fragments. Restriction enzymes are frequently used in biotechnology to analyze and make new DNA molecules.

Typically, the analysis of DNA using restriction enzymes involves a technique called agarose gel electrophoresis.

• Agarose consists of chains of sugars, and has a consistency similar to gelatin when used for this purpose.
• An electric current moves the DNA through the agarose, and the DNA molecules separate according to their size, with the smaller DNA molecules moving faster.
• The bands of different-sized DNAs are then detected by means of a dye added to the gel.

One of the easiest ways to incorporate these techniques in the classroom is to do a combined restriction enzyme digestion & agarose gel electrophoresis laboratory exercise. Typically, students would do a restriction enzyme digestion on an inexpensive, readily available DNA, then run that DNA in an agarose gel. Students would then analyze the pattern of different-sized DNA bands.

A number of articles describe laboratory activities that deal with this topic.^14,16,17,21 In addition, all the companies listed in the previous two sections sell pre-packaged kits that demonstrate these techniques. If your budget does not allow conducting wet labs, a number of simulation activities have also been developed.^{16,24,26,29,30}

Polymerase Chain Reaction

The PCR (Polymerase Chain Reaction) has become a common biotechnology technique for the production of multiple copies of relatively short DNA molecules. This method is somewhat analogous to a molecular copy machine for pages (short sections) of DNA. PCR requires

• DNA that will act as a template
• short, single-stranded DNAs called primers (starting points for making DNA)
• an enzyme that makes DNA
• the building blocks of DNA called nucleotides
• a machine called a thermal cycler, which repeatedly subjects the reaction mixture to varying temperatures

There are a number of ways to incorporate PCR into the classroom. Simulations of PCR can enhance student understanding of the methodology without the need for equipment and supplies.^8,16 Basic equipment, such as two or three water baths, can be used to perform the reactions if a thermal cycler is not available. For advanced classes, several exercises using a thermal cycler could be included.^5,11,25 There are commercial pre-packaged kits for doing PCR in the classroom.

DNA sequencing

DNA sequencing is the heart of the human genome project, and is indispensable for many biotechnology projects. The purpose of DNA sequencing is to determine the exact order of bases (letters) in a DNA molecule. This information can then inform a scientist about the nature of a protein encoded by that DNA, the likely evolutionary relationship between different organisms, and a wealth of other information.

There are many avenues for incorporating DNA sequencing into the classroom. These include

• simulations done with pencil and paper^16,18
• downloading and analyzing real sequence data over the internet^19,22,23,27
• having students prepare DNA (e.g., through PCR, as described above), sending out the DNA for sequencing, and then analyzing the sequence data¹³

One of the best places for information about the last option is the Dolan DNA Learning Center site.¹¹ They have developed a kit for doing PCR from students’ DNA (available through Carolina Biological Supply Company) and, currently, they will sequence that specific DNA for free.

Microarrays

Until recently, when it came to answering questions like “Which genes are expressed in cancer cells that aren’t expressed in normal cells?,” a very laborious gene-by-gene analysis was required. Techniques using microarrays are now available for simultaneously analyzing the expression of many genes. These microarrays are made on either a glass slide or silicon chip, and contain hundreds or thousands of parts of genes in a small section of the slide or chip. In this procedure, the expressed genes are isolated from cells, after which those genes are detected by determining which DNAs on the chip bind to which genes from the cells.

Wet lab exercises are difficult with this technology, since it is quite new and the supplies and equipment are expensive. However, students can experience microarrays in several ways, including viewing examples of microarray data6 or viewing an internet-based simulation describing how gene expression is studied using microarrays⁷. Many companies that manufacture microarrays have information for educators on their websites.¹

Social and ethical issues relating to biotechnology

Biotechnology applications have generated many social and ethical controversies. In a biology classroom, I think the best approach is to help students understand the information behind developments in biotechnology so they can develop a fact-based understanding of the potential benefits and risks associated with these techniques. Some examples of biotechnology-based controversies include:

• genetically modified foods
• genetically engineering microbes for bioremediation
• cloning whole organisms
• embryonic stem cell research
• gene therapy
• genetic testing

Background information on many of these controversies, and some excellent suggestions for dealing with these issues in the classroom, is found in a number of references.^2,16,20,28

Conclusion

Many resources are available to help teachers incorporate biotechnology lessons into their classes. The information that could be included ranges from simple to complex, from purely scientific issues to ethical issues, from lecture to dry lab to extensive wet lab activities. Because of its currency and importance in modern biology, teachers should strongly consider adding biotechnology topics to their curriculum.

© 2002, American Institute of Biological Sciences. Educators have permission to reprint articles for classroom use; other users, please contact editor@actionbioscience.org for reprint permission. See reprint policy.