Featured in PASCO’s Advanced Biology through Inquiry Teacher Guide
This manual features 22 challenging, standards-based, inquiry lab activities for AP, IB, and honors programs.
Students use physical models of chromosomes to explore meiosis and genetic variation, and use cross over rates observed in Sordaria to calculate gene distance from the centromere.
Students use physical models of chromosomes to explore the topics of meiosis and genetic variation. First, students use “paper chromosomes” to model the independent assortment and inheritance of fruit fly chromosomes. Fruit flies are a good candidate for a modeling activity since they have only 8 chromosomes, compared to 46 chromosomes in humans. Analyzing the variation in the phenotypes of five virtual offspring flies provides a springboard for students to connect the events of meiosis with its purpose of creating haploid cells and with the genetic variation that results from sexual reproduction.
Students then use “pop-bead chromosomes” to model the events of meiosis I and meiosis II and finally they determine the crossover rate between alleles that determine spore color in the fungus Sordaria fimicola. Spore color is a single gene trait with black being the wild-type form of the gene, symbolized by “+.” Tan color is the result of a mutation and its allele is symbolized by “tn.” Students determine the crossover rate by observing the arrangement of black and tan colored spores produced by a hybrid fungus (+ strain crossed with the tn strain). Using the crossover rate, students can determine the location of the gene for spore color relative to the chromosome centromere.
This experiment may require software and an interface for data collection.