In Lesson 3, students learned how DNA can be used to determine the evolutionary relationships among a set of organisms. We focused on mechanisms to increase the quantity of DNA (like retroviruses) and discussed how analysis of endogenous retrovirus DNA insertion events contributes to our understanding of evolution.
With HSPE testing last week, we only had two days of class. The first day was spent completing question 1 from the virus mutation worksheet from Lesson 1. Students also had an opportunity to make corrections to quiz 2. To earn a grade jump, students had to complete the following for each incorrect answer:
1. Explain their thought processes behind each incorrect answer.
2. Explain why they think their new answer is correct.
On the second day, we watched episode 2 of the new Cosmos series in which Dr. Tyson describes the process of evolution. Students should be able to explain the difference between natural and artificial selection, as compared and contrasted with the evolution of dogs and polar bears.
On Wednesday, we kicked off the Evolution unit with our first lesson. In Lesson 1, students watched a video about the evolution of soccer and then brainstormed other everyday things that have evolved over time. Student ideas included the evolution of vehicles, animals, society, technology, and medicine. In the lesson, students learned that DNA can change through missense mutations, nonsense mutations, and frameshift mutations. After the lesson, students worked with a partner to investigate a hypothetical scenario requiring the integration of research skills, critical reading skills, recollection of the Central Dogma, and application of DNA mutations. The investigation will conclude on Monday. By the end of class Thursday, most students had successfully answered questions 2-6 of the worksheet. As the events of 1995 and 2000 were before many of the students were born, we watched the following videos to bring closure to that part of the investigation and to introduce students to part of Seattle cultural history.
On Tuesday, we watched a NOVA ScienceNOW episode hosted by Neil deGrasse Tyson. The show addressed the question, “Can We Live Forever?” Students then turned in their responses to three questions on a worksheet. Humans continue to develop amazing biomedical tools which may someday enable us to replace human parts just like car parts, potentially extending the human lifespan indefinitely. This provides a stark contrast to the traditional concept of evolution, where DNA mutations accumulate over many generations and may provide individuals with a survival advantage. In the rapidly approaching future, where biomedicine can overcome genetic defects and introduce new organs or even new traits, will we have to reconsider our definition of the process of evolution?
We are wrapping up the Genetics Unit and transitioning to the Evolution Unit. The Stranger Visions video is an excellent example of the merger of art, science, and technology. Give it a watch, and think twice the next time you spit out your gum!
For the Lesson 8, the final lesson in the Genetics Unit, we learned about the “Levels of Heredity” and then how to make dihybrid crosses. A dihybrid cross is a Punnett Square that shows the possible inheritance patterns of two independently-assorting genes. The classwork for this lesson included a dihybrid cross (two-trait Punnett Square) worksheet and a reading with questions about the connection between Down Syndrome and Alzheimer’s Disease.
We will have our second quiz for the Genetics Unit on Friday, so study hard! Be sure to review Lessons 5-8, focusing on mitosis and meiosis, vocabulary (allele, genotype, phenotype, dominant, recessive, homozygous, heterozygous) and know how to make and analyze one- and two-trait Punnett Squares.