# Mitosis Movie/Meiosis Simulation

By
William C. Johnson
San Benito High School

Here's where BBB teaches

# The Mitosis Home Movie

You realize by now that the cell is a complex thing.  It "multiplies by dividing".  Its not quite like cutting a cube of butter in two - the cell is at least as complicated as a car, and you'd hardly take lightly if you saw a car produce a copy of itlelf!  Its amazing how the intertwined, involved structuresseparate neatly and evenly.  Yet the process goes on rappidly, and insome cells, happens daily.
To get a clearer idea of this process we're hoing to make a movie--the kind where you draw pictures of something happening in a series of small steps on the edges of cards....and then when you flip the cards, you have action. Let's make a movie of animal cell mitosis!   We'll use the cells pictrued below as the 6 dey cards for the stages.  In between each pictured card, you will draw in 3 steps between them.  Movies in color are better, so use colored pencils or pens to jazz it up.  You'll need a total of , let's see 6 + 18 equals 24 cards!  On the back of each key card tell what's going on--like interphase-- contrioles form asters and move apart. You'll also need one card ant the beginning for the movie title, and one at the end for the credits - the name of the producer.  When you're done with your movie, show it to your teacher, and turn it in with a rubber band around it.

# Meiosis Simulation

### The Activity

This is open to your imagination. The basic idea is to get the kids to see by direct involvement what the process of each type of division is in terms of the role of chromosomes in each process. Basically, I had several volunteers come in during lunch (or break) and go through the process of meiosis. First they chose a partner they wanted to share a homologous chromosome with. Once I had them in pairs, I gave them each a chromosome one student with a maternal chromosome (“a” or pink) and their partner with the paternal homolog (“b” or blue). We then went through the process as outlined below to prepare for the class presentation.
The students lined up in front of the class, boldly presenting their chromosome to the class.  I mentioned that we were in interphase I of meiosis and ready to make some gametes.   To simulate the replication of the chromosomes in late interphase, I had them put the matching half of their assigned chromosome in their back pocket.  At the end of the “S” stage they would pull it out and put them together (velcro or snap) to make a pair of identical chromatids held together by a centromere. (I took time in each step to have those not directly invowed tell me what phase we were in and what was going on.)
At this point imagination will guide you as to how you want to continue your simulation.  I chose two “class organizers” to act as centromeres they would move to opposite sides of the rom or the area we were in.  they had a cord (nylon string) for the number of pairs of chromosomes in the simulation (I have 9 pairs in mine, therefor, each centromere has 9 cords).  These cords represent the microtubules of the spindle.   After replication of DNA the pairs were told them to 'line up with their pair. It is vital that everyone understand that the homologs lined up on the cell equator on a random basis, and that no pair had previously discussed with each other nor with any other homologous pair just how they were going to line up during tetrad formation. The next step was to separate the chromatid pairs from each other.  Eadh centromere would hand a cord to the person (of each pair closest) and “pull that person with their two chromatids toward the organizer.   Make sure they see that the duplicated chromosomes traveled as a pair, and are not torn apart as in the first division of mitotic anaphase. Take  time to analyze what has occured.  Each organizer has half the chromosomes around them and they represent a random combination of maternal and paternal chromosomes (Haploid).
The final step is gamete formation. Have each of the students tear apart the chromatids, putting one in each of 4 boxes provided.
Repeated simulations will reinforce the random assortment of chromosomes.  When dominant and recessive alleles are placed on the chromosomes students will see the principle of segregation.   Make a tally on the board of the gametes made, and it will show gametes genetically different from the parent; not only in genotypes, but also in the total number of chromosomes in the gamete.  Go through several rounds, showing that each round could produce different gametes depending on the random tetrad formation in metaphase I of meiosis. Finally,  cross several gametes from different rounds to get genetically different individuals. Depending on background you may want to talk about different genotypes/phenotypes etc.   It is  also a good time to compare this to mitosis which gives genetically identical outcomes to make the point that these different processes have different results because they have different purposes. Again, there are many ways to go with this and it is totally up to your creativity.

### Sea urchin project

Here is a page on sea urchin bioasssay