Name:___________________________________________  Period:________________


Breeding Reebops


Have you ever wondered why there is so much variation among members of the same family? Today you are going to try and answer that question.


At the front of the room are Mom and Dad Reebop. They are the “parents” of all the reebop offspring that will be produced in this class. You have an envelope of chromosomes representing Mom (pink) or Dad (blue). Mom and Dad Reebop each have eight pairs of chromosomes for a total of sixteen chromosomes all together. Make sure the lab group across the lab station from you has the opposite color.



  1. Dump out the chromosomes on the lab table.
  2. Find the X and Y chromosomes. These are the sex chromosomes. The “Mom” should have four X chromosomes and the “Dad” should have two X chromosomes and two Y chromosomes.  Set these aside.
  3. Turn all of the other chromosomes printed letter side down and organize the chromosomes by length. Don’t worry about the numbers on the back of the chromosomes. These are called homologous chromosomes.



  1. You should have four copies or two sets of chromosomes for each length. Cross them like the letter “X”. This is called a tetrad. Tetrads form during Prophase I of meiosis.
  2. The eighth set of chromosomes should be the sex chromosomes. Place these after the shortest chromosomes. Again, “Mom” should have four X chromosomes and “Dad” should have two X chromosomes and two Y chromosomes.
  3. Rearrange the tetrads so they are lined up end to end the way they would appear during Metaphase I. You will need to use the length the of the lab table for this.
  4. Randomly separate one set of chromosomes from the other set of chromosomes. DO NOT concern yourself with the numbers on the back of the chromosomes. This represents Anaphase I when the homologous chromosomes separate and move to the opposite poles.




  1. Separate each set of chromosomes so you end up with four groups of chromosomes. This represents Anaphase II when the centromeres split and each individual chromosome moves to the opposite pole.

9. Each column of eight chromosomes is a sex cell. You have now created four egg cells each with eight chromosomes (the pink chromosomes) or four sperm cells each with eight chromosomes (the blue chromosomes.)

10. Randomly pick two groups of chromosomes representing two of the sex cells and place them back in the envelope.

11. Now randomly pick one of the remaining two groups of chromosomes and switch with the lab partners across the table. You should now have a group of eight pink chromosomes represent an egg cell and a group of eight blue chromosomes representing a sperm cell. Are these sex cell haploid or diploid? ______________________

12. HAVE SEX!! During fertilization, the sperm cell and the egg cell fuse to make one zygote. Put the chromosomes together and turn them printed letter up. Is the zygote haploid or diploid? ___________________________

13.  Pair up the chromosomes by letter (this should also correspond to length). The exception to this would be if you have one X chromosome and one Y chromosome. Those should be paired together.

14. There should be sixteen chromosomes for the baby, half pink and half blue. Circle below the chromosomes that came from each parent and then print the baby’s genotype (letters) in the spaces provided.


From Mom (pink)                 From Dad (blue)                                Baby’s Genotype


A         a                                  A         a                                              _______________


M        m                                 M        m                                             _______________


Q         q                                  Q         q                                              _______________


T         t                                   T         t                                               _______________


E         e                                  E         e                                              _______________


L         l                                   L         l                                               _______________


D         d                                  D         d                                              _______________


X         X                                 X         Y                                             _______________


Use the decoder below to identify the traits of the baby Reebop. Circle the combination.


AA = two antenna                                          EE or Ee = two eyes

Aa = one antenna                                            ee = three eyes

aa = no antenna


MM = one green hump                                   LL or Ll = blue legs or green legs

Mm = two green humps                                  ll = red legs or yellow legs

mm = three green humps


QQ = pink nose                                               DD or Dd = three body segments

Qq = orange nose                                            dd = two body segments

qq = yellow nose


TT or Tt = curly tail                                         XX = female

tt = straight tail                                               XY = male


Draw your baby below. Use colored pencils to show detail.



























Use the materials supplied to construct you baby Reebop.


Antenna = paper clips                                     Eyes = thumbtacks

Back humps = green mini marshmallows        Legs = push pins

Nose = mini marshmallows                             Body segments = large marshmellows

Tail = pipe cleaner                                           Male organ = straight pin

Use toothpicks to hold pieces together (ligaments and tendons)


14. Fill out the birth certificate. (Name your baby, write today’s date, list your names under “Delivered by”, and record the sex of the baby.

15. Place your baby on its birth certificate in the “nursery”.




  1. What does diploid mean?



  1. What does haploid mean?




  1. Are Mom and Dad Reebop’s body cells diploid or haploid (refer to step 3 of the procedure)?



  1. What type of cell division did this activity simulate?



  1. What are homologous chromosomes?




  1. How many sex cells were made from one parent Reebop during meiosis?



  1. Are the sex cells made during this activity diploid or haploid? (refer to step 11 of the procedure)?



  1. Is Baby Reebop diploid or haploid? (refer to step 12 of the procedure)?



  1. Look at all of the other Reebop babies in the “nursery”. Are any of the Reebop siblings exactly alike?



  1. What are the two processes that occur in meiosis that cause all of our sex cells to be different from each other?



  1. Describe independent assortment.




  1. What is the end result of meiosis (# of cells, compare the cells and # of chromosomes)?