As a review from yesterday and to extend student learning of Punnett Squares to dihybrid crosses, we began class with the following video by Mr. Anderson of Bozeman Science:
Students took notes throughout the video, with emphasis placed on understanding the connection between meiosis and fertilization (as represented by the Punnett Square), sex-linked traits, and how to determine the alleles in a dihybrid cross. After the video, we reviewed how to identify the alleles, with pictures from the white board shown below:
We then worked through questions 1 and 2 of the dihybrid cross worksheet (pictured below), as well as portions of questions 3 and 4.
Students learned to construct and analyze the products of a dihybrid cross (two-trait Punnett Square) today. We worked through the entry task slide using the white boards and document camera in class to ensure student understanding of the process. Slides 3-7 of the attached PowerPoint deck were not presented in class, but are included as an example for students needing to review. Students then had the remainder of the class period to complete the dihybrid cross worksheet.
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.