Biology is a fascinating field of study that is literally full of life! From the atoms that come from distant stars to our cells, microbes, and atmosphere, biology plays a role in our daily lives. As biology content writers, we must ensure that our teachers and students know how to reason scientifically. This will enable scientifically literate adults to understand that theories change over time. They will then better realize the importance of big ideas like the Tree of Life, Central Dogma of Biology, evolution, and ecology.
- Scientific Reasoning
In order to fully understand biology, students must learn How Science Really Works. In science, we do not call an idea a theory until it has been proven over and over again by different people, using different methods, in different institutions. Just like our Constitution, scientific dogmas and theories can be amended over time as new information is gained. Without knowing how science works, it’s easy to discount important concepts like evolution as “just a theory.”
Luckily for us, what makes biology exciting is its unpredictability. Therefore, it’s more important for students to troubleshoot their way through procedures that vary in results than to make sure all students get the expected answers. Argument-Driven Inquiry in Biology helps students design, conduct, and analyze their own experiments. To avoid student frustration, temper your inquiry lessons, like those given at Exploring the Scientific Method, with a few guided experiments that produce expected but variable data (for example, Effect of Size on Uptake by Diffusion).
- Archaea Are Not Bacteria and No Longer Called Archaebacteria—Maybe Not Even Archaea!
In 1990, Carl Woese used ribosomal RNA to generate a Universal Phylogentic Tree that had three domains: archaea, bacteria, and eucarya. However, many modern-day articles and textbooks persistently call archaea by their original name, archaebacteria. This leads to the misconception that archaea are a type of bacteria, when in fact archaea are more similar to eucarya than bacteria.
The word bacteria was taken out of “archaebacteria” because, although the two types of organisms look very similar (unicellular, microscopic, prokaryote), they are structurally and chemically different (summarized in University of Colorado Boulder lecture notes). Many biologists theorize archaeans are the ancestors of all life. More recently, an archaeal origin of eukaryotes is thought to support only two primary domains of life. In 2016, scientists unveiled a new Tree of Life, where archaea and eukarya are separated and located at the bottom of the tree, whereas bacteria occupy a much larger group at the top of the tree. Obviously, the Tree of Life continues to be revised!
- The Central Dogma of Biology Has Exceptions
In 1956, Francis Crick posed the Central Dogma of Biology to explain how genetic information flows from DNA to RNA to protein. In 1970, his Nature article included evidence for DNA to DNA, DNA to RNA, and RNA to protein transfers. Interestingly, Crick had the foresight to write that any future discovery of cells that transfer protein to DNA “would shake the whole intellectual basis of molecular biology.” This is exactly what happened when Stanley Prusiner proposed the Prion Theory that proteins can act as infectious agents with the transfer of protein to DNA (read more at Does the Central Dogma Still Stand?).
An important lesson of the Central Dogma of Biology is that changing a single nucleotide of DNA may tremendously impact the protein for which it codes as well as alter the organism’s phenotype. Mutations to DNA can be harmful—as in those that cause cancer and disease—but can also be beneficial, as in those that allow the organism to adapt and evolve (see From DNA to Disorder).
How to teach both the most common transfer of information in organisms, as dictated by the Central Dogma, along with less-common transfers like prions? Include epigenetics in your biology course. Several lessons can be found in “Epigenetics/Inheritance and the Environment” of GeneEd Teacher Resources.
- In Biology, Ecology Is the Big Picture and Evolution Is the Crowning Achievement
There is a disparity between biology faculty and students concerning what concepts are important in general education. Faculty rank scientific reasoning as most important, followed by the cell and evolution. However students rank scientific reasoning and evolution (along with ecology) as least important. This suggests students are missing the most basic scientific tenet: that facts, dogma, or theories can change as new evidence arises. Without this knowledge, students “can’t see the forest for the trees.”
Some curricula are so loaded with vocabulary and facts that students are getting a disjointed, disconnected view of biology. This hinders them from understanding big-picture concepts like ecology, which requires students to make intellectual leaps and associations between ideas. Additionally, students unschooled in the nature of science may think evolution is relatively unimportant.
Biology course writers need to explicitly address these misconceptions and ensure their curriculum includes a unit on the nature of science. This could be followed by a discussion of the Tree of Life and domains, the cell, and the Central Dogma of Biology—which should include an introduction to mutations. After learning about genetics and populations, students will then be ready for natural selection, evolution, and ecology, which tie it all together. Tons of lessons are available at Evolution and the Nature of Science.