Climbing the Double Helix: DNA Lesson Plans
With the right DNA lesson plans, students can learn about the structure and function of DNA.
By lynseyrpeterson@hotmail.com
I am always amazed when I think about how recently humanity learned about DNA. It was less than 60 years ago when James Watson and Francis Crick identified the structure of the double helix. Since that time, a basic understanding of DNA has been infused into popular culture – consider the popularity of CSI! Because of the practical implications of a study of DNA, students usually find this subject fascinating.
Students have undoubtedly heard of DNA, but usually do not know what the acronym stands for, about its structure, or how it was discovered. I start off by telling my students the story of DNA’s discovery. They learn about the x-ray pattern of DNA uncovered by the work of Rosalind Franklin and Maurice Wilkins that set the stage for Watson and Crick's DNA model. The marginalization of Franklin’s work also makes for an interesting tale. Next, I have students do a DNA extraction lab. Below you can find lessons that give directions for how to conduct a DNA extraction experiment. I have used wheat germ successfully, but have found strawberry extraction to be the easiest and most effective. Students cannot believe that the snotty substance they produce is DNA.
After students have seen DNA themselves, I teach them about its molecular structure. I relate the molecular double helix to the DNA students extracted by using the analogy of a thread to a thick rope made of many threads. You cannot see a single thread across a football field, but you can see a thick rope. To help students learn about DNA structure, I have them make a model. While making a model, students learn about the parts of the nucleotides and the base pairing rules.
Once students have made their models, they should find it easier to understand how DNA unzips to replicate itself. I emphasize the importance of DNA replication in subjects that we have previously discussed, such as mitosis. At this point, I always check for understanding so that I can be sure that my students are ready to move on to learning about the transcription and translation of DNA to make RNA and proteins. What follows are DNA lesson plans that can help students learn about its structure and function.
DNA Lesson Plans:
Students work on this lab in cooperative groups of four, and manipulate nucleotides to discover the structure of DNA. When they have finished the lab, students have produced a model of DNA that can be hung on the ceiling. Students use this model to serve as a visual aid as they discuss mitosis, amino acid sequences and protein synthesis.
Students research the historical development of DNA research. They complete the DNA Restriction Analysis lab at Cold Spring Harbor Lab. Students discuss the Nobel Laureates who have worked at the lab.
Students extract DNA and test for its presence from unroasted (raw) wheat germ using a prescribed procedure. They modify the procedure to provide a less expensive, easier method. They also extract DNA from different available plant, animal and/or bacterial sources. The yield of DNA is then compared.
Students interpret different DNA fingerprints, then do a jigsaw activity to explore other uses of DNA forensics. They listen to a radio program about using DNA as evidence, and discuss the limitations of and problems with DNA testing.