Teacher Instructions:
The general sequence for students in this simulation is:
- Pass out pink chromosome pages to the wives, and blue to the husbands. Wives cut out all the autosomes and XX, husbands cut out autosomes and the Xy chromosomes.
- Cut the 23 chromosome pairs out around the outside edge of the pair (solid line).
- Fold the chromosome pair along the mid line (dotted line).
- Tape or glue the chromosome pairs together back to back.
- Get "married" and understand many of the responsibilities that result as a consequence of this important commitment.
- Dropping, spinning and grouping 23 pairs of chromosomes to impart randomness, thereby simulating gamete formation. Each one of the pair which is face up, represents the "successful" member of the chromosome pair which enters the student's sperm or egg.
- Pairing ... pushing together the maternal and paternal chromosomes (alleles) to represent fertilization.
- Determining the genotypes and resulting phenotypes of the "children" produced by one successful fertilization.
- Creating clever birth announcements including artwork, poetry, or other media. This should include all of the phenotypic descriptions that the students generated.
- Drawing the face of the children as they would look as young teenagers. (Their own age.)
The more specific sequence for this simulation is:
Constructing Model Chromosomes
- When introducing this activity, it is best to walk your students through the chromosomal construction process.
- You should demonstrate:
- the cutting and folding of the chromosome.
- the folding glue/taping of the pair of chromosomes.
- the test dropping of the pair of chromosomes. Make sure they spin to the floor; it's like flipping a coin to impart randomness.
Cut and glue/tape the chromosomes: Your students will go home and cut out and prepare the chromosomes for the next day. Have them make sure that all the chromosomes that they make spin properly. Doing these things at home saves valuable class time for other activities. Have them place all the chromosomes in an envelope and place them inside a book for transportation. This keeps the folded, paired chromosomes nice and flat.
- Marriage: The next class day, your students will actually simulate getting married. Married couples are more likely to be financially and emotionally able to make the ultimate commitment.... raising a healthy, happy baby which can reach full potential. In addition, our experience shows that junior high school students exhibit some embarrassment with aspects of this topic because of their age-appropriate social immaturity. The teacher needs to take time to talk about the whole activity in advance and assure the participants that this is only a simulation and has no other implications. If the teacher assigns the pairings, the students will be relieved of embarrassing choices to make. If the students are allowed to make their own "marriage" choices, there may be a few too many boys or girls left over. Crazy as it may seem, I have handled this by creating "widows" and "widowers" who are then free to remarry someone else.The students are then paired up, and a short lecture by you, the "preacher", about being financially and emotionally committed to a long-term, loving relationship (the only proper environment for nurturing children in this world) is followed by a short "marriage" ceremony.
Making Gametes: The married couple is encouraged to move as far away from each other as possible; this prevents any mix-up in the genetic material. Each partner of the "married couple" then holds the paired chromosomes above her/his head, and drops them to the floor to form two separate piles; the male's pile of blue chromosomes, and the female's pile of pink chromosomes. This symbolizes the randomness associated with the chromosomal gymnastics of gametogenesis (meiosis). Naturally, only one of the sides of the chromosomal pair ends its journey facing up; this represents the one chromosome of the pair that ends up in the successful gamete after meiosis. The separate piles of chromosomes on the floor contain the unique assortment of alleles that each member of the couple will contribute to the potential offspring -- the "successful" gamete. The students should be careful not to reshuffle the chromosomes by turning them over by accident during the next process.
Getting ready to mate! These 23 single chromosomes can be gathered up at this point and organized by sex on the lab tables. The husband and wife should face each other with the table in between them. The husbands will organize their chromosomes with the X or Y chromosome on the far left and the rest of the chromosomes by size from the smallest (left) to the largest (right). The girls will organize their chromosomes with the X on their right and then by size from largest (left) to smallest (right). This places the chromosome alleles across from each other when the married couples are facing each other at the tables.
Successful mating; a baby is started! Starting with the sex chromosomes, and then advancing from the #1 to #22 chromosomes, both male and female rows of chromosomes are pushed together and the alleles paired up side by side; this represents the process of fertilization. There are now a pair of each of the 23 chromosomes; enough to start cell division, produce an embryo, fetus and, finally, nine months later the baby.
What does the baby look like? The parents copy down the resulting genotypes on the data sheet and determine their child's phenotype.
Birth Announcement: Each partmer writes a clever birth announcement enriched with genotypic and phenotypic adjectives and artwork. This causes the students to imagine what the offspring will look like and to realize that the chromosomal/gene gymnastics that take place during meiosis and the unification of genes during fertilization make babies of incredible beauty, complexity and variety. You are causing the student to realize that the genotypes on the chromosomes produce phenotypic (protein-based) structures in the child..
The child grows up! After the married couple has determined what the baby will look like, and has produced a adjective-riddled birth announcement, it is time to raise the baby. For fifteen long years they change the diapers, feed, love and care for the child. They nurture their offspring in every way possible. Finally the product ......a fifteen (whatever age your students are) year old, going to high school, learning neat things, hooking up brain cells, meeting new people, having new experiences, loved and loving human is produced. What does their offspring, the child that they are so proud of, look like? Create a full page drawing of the child's face. This should be done at home, not in collaboration with the partner. Each parent will draw the child. Your students have various art backgrounds so it might be wise to have them look at a few photos of people's faces and measure where things are! The name of the child is not placed on the front of the portrait. The next day the students bring in their drawings and tape them up in the classroom at random. You, the teacher, will try to match up the two drawings done by the parents. They are surprisingly easy to match!
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