I have just returned from the regional conference of the National Science Teachers Association (NSTA) in Cincinnati, Ohio. As usual, I’m filled with inspirational new knowledge regarding science and instructional approaches. I have already created a review activity using my newfound knowledge, not 24 hours post-conference, and I cannot wait to implement it this week!

But there is a rub with attending these conferences, one that I think all science teachers are familiar with. That is the ever-present fact that I cannot keep abreast of the latest scientific findings or make quick and easy decisions about how to use the breakthroughs in age-appropriate, pedagogically sound ways, aligned with standards.

For example, I attended a talk regarding some outcomes of the Human Genome Project. This was the largest scientific endeavor ever attempted in the history of science. Fifteen years later we now know that 98.5 percent of our DNA is “junk” or noncoding; we have about 20,000 genes and 100,000 proteins! How then can we get 100,000 proteins from only 20,000 genes? Enter complexity.

“Noncoding” refers to DNA that does not get translated into a protein. However, this does not mean that it codes for nothing. Got that? It is now known that there are actual genes in the noncoding regions. What? Wouldn’t that make them coding then? No, because they don’t code for proteins, they code for microRNAs. These pieces of RNA are 22 base pairs long and attached to the 3′ end of a gene, and through negative feedback, silence the gene.* Five hundred of these microRNAs have been identified. It turns out that DNA is a blueprint coding not just for proteins but also for gene silencers. Thus, it may be possible to silence a host of disease-causing genes such as the Huntington’s Disease gene. How exciting is that? We have Andrew Fire and Craig Mello to thank for this breakthrough.

But I have not answered the question regarding how we get 100,000 proteins from 20,000 genes.  After transcription, the microRNA, which by the way is now referred to as the transcript, consists of alternating sections of exons and introns. The introns do not contain protein-coding information and are excised. The exons are then spliced together to construct the gene to be translated. However, those exons can be spliced together in various sequences, creating various protein codes. Other species do not have this process, thus they need more genes. This is relevant, worthwhile information, but when, how and how much of it do I present to my students?

NYTimes.com recently published a related article, Scientists and Philosophers Find the ‘Gene’ has a Multitude of Meanings. It seems geneticists are OK with the variation in meaning of terms as this is consistent with the nature of science. As they gain new understandings, conceptual understandings change. So geneticists are fine with using the same terms while they simply modify the associated meaning. But laypeople, including philosophers, propose we use new terms for new conceptual knowledge. For example, “dene” could replace gene, and could capture the concept of noncoding DNA.

I think I prefer the scientists’ perspective: anything to avoid adding new vocabulary to an already bloated scientific vocabulary. With this perspective, I don’t feel obligated to introduce new terminology to my students, so that’s a relief. But I will continue to struggle with keeping abreast of the latest scientific findings as well as what, when and how to present new findings to students. When that struggle ends, I’ll know I’ve retired!

Here are some science education-related resources from the National Science Digital Library Middle School Portal that may assist you in both science content and pedagogical content knowledge: The USGS and Science Education; The Science Education Gateway (SEGway); and Science Education on the Web: Athro, Limited.

*For a more detailed explanation and concise definition of dsRNA see http://www.clontech.com/support/tools.asp?product_tool_id=54329&tool_id=54336. For information regarding “dicer,” the enzyme that enables the gene silencing in concert with the microRNAs See http://www.als.lbl.gov/als/science/sci_archive/120dicer.html.

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