Mitosis

Meiosis Modeling Activity


Subject:
This lesson is appropriate for a biology or life science curriculum.
Grade Level:
I use this in my 9th grade class although it could be adapted for any secondary classroom.
Topic:
The topic of the lesson is meiosis. As a result of this lesson students will be able to model the process of meiosis in a cell with two homologous chromosome pairs.
Lesson:
Teacher Prep:
Before you begin this lesson you must set up the document camera. I use it attached to a PC but you could also connect it directly to an LCD projector. You must make a class set of the ‘Modeling Meiosis’ worksheet found at the end of this lesson. Further, you must create model kits for the students. Figure 1 shows you a picture of my kit. You can make this using any type of beads or string.
Figure 1

Student Activities:
Pre-Lab:
I begin this activity by handing out the worksheet and asking the students to complete the pre-lab questions. As they answer these questions I walk around the room and hand out the model kits. After they have all had the opportunity to complete the questions I ask them to remove the contents of their model kits from their bags.

I then ask the students to model their answer to #1 using the contents of the kits.

• Draw a tetrad in the space below and label the following: centromeres, sister chromatids, homologous chromosomes.

I ask one student to come to the front of the room and model this using the document camera. Once the student has done so, I click the freeze button so that all students can review their answer.

Next I go over the answer to #2.

• What are the two elements of meiosis that add variation to our population? (Hint: one occurs in prophase I and the other in metaphase I).

I again ask one of the students to come to the front of the room and this time to model crossing over. I keep the document camera frozen on the previous answer until the student is finished setting up his/her model. Then I unclick the freeze button. I repeat these steps as a student models independent assortment.

Lab:
From here we go through each phase of meiosis using the directions on the worksheet. First students model the phase at their seat then we go over it as a class checking our work against the model captured by the document camera. I have students take turns coming up to the camera and modeling for the class. I use the freeze button between each phase so the students must attempt each model at their seats. This allows the students using the document camera to ‘unveil’ their model when everyone is ready.

I like to go through the modeling activity twice so that I am sure students have mastered each phase of meiosis.

Conclusion:
Once we have completed the modeling activity twice. I give the students some time to complete the conclusion questions on the back side of the worksheet. Once everyone has had the chance to complete the questions I place my worksheet under the document camera. I place a blank sheet of paper over the answers and slowly move the blank sheet down the paper as I go over the answers.


Meiosis Modeling Activity

Pre-Lab:
• Draw a tetrad in the space below and label the following: centromeres, sister chromatids, homologous chromosomes.



• What are the two elements of meiosis that add variation to our population? (Hint: one occurs in prophase I and the other in metaphase I).


Lab:
Phase Modeling
Prophase I Create tetrads (XX) by pairing homologous chromosomes. Model crossing over.
Metaphase I Line up your tetrads along the metaphase plate. Model independent assortment.
Anaphase I Move the homologous chromosomes to opposite ends of the cell.
Telophase I You should have two chromosomes in each of your two nuclei.

Cytokinesis I Divide your cell membrane so that you have two daughter cells.
Prophase II Check to make sure that each of your two cells contains two chromosomes made up of sister chromatids.
Metaphase II Line your chromosomes up along the middle of each of your cells.
Anaphase II Separate your sister chromatids. Move one sister chromatid from each chromosome to opposite sides of your cell.
Telophase II You should now have four nuclei, with two single chromatids in each of the cells.
Cytokinesis II Divide your cell membranes so that you have four daughter cells.


Conclusion:

1. Think about your modeling. Visually, what is the major difference between prophase I and prophase II?


2. What is crossing over? When does it occur during meiosis? How did you model this element of meiosis?


3. Think about your modeling. Visually, what is the major difference between metaphase I and metaphase II?


4. What is independent assortment? When does it occur during meiosis? How did you model this element of meiosis?


5. Which part of meiosis, meiosis I or meiosis II, is responsible for halving the number of chromosomes?