Download ReeBop Investigation

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