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ReeBop Investigation Background: ReeBops are small organisms that live in discarded soda cans. Chances are you have never seen one as they are extremely fast little organisms. Chromosomal analysis of ReeBops has revealed that they have 7 pairs of chromosomes for a total of 14. Objectives: 1. To combine genetic traits obtained from the “father” with genetic traits from the “mother” to create a ReeBop. 2. During Meiosis of the “father”, students will show crossing over of a specific gene. Meiosis of the “mother” will have no crossing over. 3. Show how crossing over adds to the diversity of the next generation 4. Use the key below to determine traits of ReeBops. Legs Legs Tail Humps Body Segments Wings Legs Eyes Nose Antenna Sex ReeBop traits key LL= long legs Ll = long legs RR = red legs BB = yellow legs TT = curly tail Tt = curly tail MM = 2 humps Mm = 2 humps DD = 3 body Dd = 3 body segments segments WW = 4 wings Ww = 4 wings NN = 6 legs Nn = 6 legs EE = 2 eyes Ee = 2 eyes QQ = blue nose PP = yellow nose AA = 2 antennae Aa = 2 antennae XX = female XY male ll = short legs RB = orange legs tt = straight tail mm = 3 humps dd = 2 body segments ww = 2 wings nn = 4 legs ee = 3 eyes QP = green nose aa = no antennae YX = male Procedure: A. Mother’s genes 1. Add this table to your notebook. Use the title “Mother’s Data”: Leg length Leg color Tail Humps Body Segments Leg number Wing number Eye number Nose Antenna sex Leg length Leg color Tail Humps Body Segments Leg number Wing number Eye number Nose Antenna sex 2. Begin with the mother’s envelope, put the father’s genes aside. Do not mix up genes. 3. Sort the homologous pairs of chromosomes (tetrads). Chromosomes are the same length and have different alleles in the same location. There should be four chromatids for each, two pink from its mother and two blue from its father. 4. Line up homologous chromosomes along the equator of the cell (your table). Remember the law of independent assortment and different colors will be on different sides of the equator, not all the same. Sister chromatids should be paired up so both pinks will be together and both blues together. 5. Using the chart provided, determine the genotype and phenotype of the mother ReeBop and record in your notebook. 6. Perform Meiosis I. Separate homologous chromosomes into two new cells. 7. Perform Meiosis II. Separate sister chromatids into four gametes (eggs). 8. Flip all four gametes upside down so you cannot see letters. 9. Randomly select one of the gametes (eggs). Put that gamete aside and place the other three back in the mother envelope. B. Father’s genes 1. Add the same table to your notebook for “Father’s Data”: 2. Empty the contents of the father envelope onto your table. Make sure not to mix up these chromatids with the mother’s gamete you separated. 3. Sort the homologous pairs of chromosomes (tetrads). Chromosomes are the same length and have different alleles in the same location. There should be four chromatids for each, two pink from it’s mother and two blue from it’s father. (Same as step 2 above) 4. Line up homologous chromosomes along the equator of the cell (your table). Remember the law of independent assortment and different colors will be on different sides of the equator, not all the same. Sister chromatids should be paired up so both pinks will be together and both blues together. (Same as step 3 above) 5. Using the chart provided, determine the genotype and phenotype of the mother ReeBop and record in your notebook. (Same as step 4 above) 6. Demonstrate crossing over. 7. After crossing over is done, perform Meiosis I and separate homologous chromosomes into two new cells. 8. Perform Meiosis II. Separate sister chromatids into four gametes (sperm). 9. Flip all four gametes upside down so you cannot see letters. 10. Randomly select one of the gametes (sperm). Put that gamete aside and place the other three back in the father envelope. C. Mate your two gametes. 1. Add the table a third time to record new ReeBop data. Add a title. 1. Pair up similar length chromatids two make new pairs in your baby ReeBop. You should have 7 pairs of chromosomes. 2. Determine the genotype of your new ReeBop. Record the genotype in your notebook. 3. Determine the phenotype of your new ReeBop. Record the phenotype in your notebook below your table. D. Build your ReeBop 1. Using materials provided by the teacher, build your ReeBop according to the ReeBop traits key located at the top. Large marshmallows = body segments small marshmallows = humps Paperclips = antennae toothpicks = legs Pipecleaners = tails wiggly eyes = eyes Transparencies = wings marshmallows = nose