MARSHMALLOW MEIOSIS LAB : Rebops Original Author: Unknown Presented by: Tracy M Harper, Western Technical College Introduction: Rebops are marshmallow ‘animals’ that have eight characteristics that are determined by their ‘genetic makeup’. Each trait is represented by both a dominant and recessive trait, which depending on how the genes are inherited, will determine the phenotype of the offspring. Rebop offspring traits are made based the genes they inherit from the parents. Learner Objectives: 1. Apply the principles of meiosis and genetic transfer of traits. 2. Determine traits of an offspring based on genetic information from chromosomes by simulating a model of meiosis. 3. Relate the genotype to the phenotypic expression of a trait. 4. Determine the mathematical probability of the genotype and phenotype of offspring produced from a Rebop sire and dam. Assessment Strategies: Teacher observation Lab activity analysis questions Time Allocation This lesson plan requires 1 hour of in class lab time, and an additional 1 hour of individual practice time to complete the assignment. LAB PREPRATATION MARSHMALLOW MEIOSIS LAB : Rebops! Materials and Supplies: Large Marshmallows Mini Marshmallows, colored Multi colored push pins Blue Pipe Cleaners Toothpicks Thumbtacks (or different colored toothpicks for the antenna) Preparation: 1. Create the eight gene pairs listed including the sex chromosomes. All eight gene pairs should be cut at different lengths. Each chromosome should have its partner cut at the same length. Each parent will have a heterozygous pair of genes, the sire’s genes are blue, and the dam’s genes are red. X L T M D E Q A X Y L l T t M m D d E e Q q a TM HARPER MANUSCRIPT, Page 2 A a q e d m t l Y Use the following traits: Physical trait Genes Supply Antenna Aa Thumbtacks Nose Qq Colored Mini Marshmallow: pink, orange or yellow Eyes Ee Thumbtacks or push pins Body Segments Bb Large Marshmallows Humps Mm Green Mini Marshmallows Tail Tt Pipe Cleaner Legs Ll Toothpicks Sex XX or XY 2. Make up at least one Rebop parent for example. MINI MARSHMALLOWS PIPE CLEANER Thumb Tacks or Push Pins MINI MARSHMALLOW MARSHMALLOW TOOTH PICK 3. Students should work in pairs for this exercise, with each pair building their own Rebop. Each student pair should start with a Sire and Dam Rebop set of chromosomes. Students will select one chromosome from the sire (blue) and one from the dam (red) for each gene pair. This mimics fertilization, where one trait is inherited from each parent, and will result will be a ‘genetic code’ for their Rebop. TM HARPER MANUSCRIPT, Page 3 4. Every student will likely end up with a different genetic code for their Rebop. However, in the event that there two identical Rebop babies…they have twins! Part II Determining Heritability 1. Have students find a suitable mate for their Rebop, allowing students to use a Rebop ‘stud’ more than once. 2. Using the Pearson Square, have students determine the probability of the expression of genetic and physical traits based on their cross. TM HARPER MANUSCRIPT, Page 4 STUDENT LABORATORY MARSHMALLOW MEIOSIS Part I: The Making of a baby Rebop 1. Select one chromosome from each parent for each trait . You should have two gene’s ( one red, one blue) for each trait. 2. Using the supplies given and the Decoder Key, construct your own Rebop. 3. Record the genotype and phenotype of your Rebop. GENOTYPE TM HARPER MANUSCRIPT, Page 5 PHENOTYPE Rebop Decoder Key AA = one antenna MM = 3 green humps Aa = two antenna Mm = 3 green humps aa = zero antenna mm = 2 green humps QQ = red nose TT = curly tail Qq = orange nose Tt = Curly tail qq = yellow nose tt = straight tail EE = 3 eyes LL = Blue legs Ee = 3 eyes Ll = Blue legs ee = 2 eyes ll = red legs DD = 3 body segments XX = female Dd = 3 body segments XY = male dd = 2 body segments TM HARPER MANUSCRIPT, Page 6 STUDENT LABORATORY MARSHMALLOW MEIOSIS: Rebops! Part II: Determining Heritability 1. Determine the sex of your Rebop by selecting a sex chromosome from each parent Rebop. 2. Select a suitable mate for your Rebop, you may use a sire more than once, but not the dam. 3. Using a Pearson Square for each trait, determine the probability of both the genotype and phenotype of the offspring. Antenna Nose TM HARPER MANUSCRIPT, Page 7 Eyes Body Segements Humps Tails TM HARPER MANUSCRIPT, Page 8 Legs TM HARPER MANUSCRIPT, Page 9