Meiosis Modeling with Beads
Cell Cycle (Interphase, Mitosis, and Cytokinesis)
You have 8 minutes to model each stage of the cell cycle as it does mitosis and discuss the questions listed below
the terms. During this, you must describe what is occurring during their substages (G1, S, G2, Mitosis (PMAT), and
Cytokinesis). In this description, you need to use the terms listed below when appropriate and know the number of
chromosomes present in the cell at the time.
 Chromatin
 Nucleus
 Nucleolus
 Chromosomes
 Chromatids vs. sister chromatids
 Homologous chromosomes
 Centromere
 Kinetochore
 Centrosome
 Spindle fibers
 Aster
 Genes
 Cleavage furrow
 Cell plate
Mitosis Questions:
1. How is the DNA in each cell in your body different?
2. If the DNA is the same, how are your eye cells different than your heart cells?
3. What type of cell would be in interphase more – skin or spinal cord and why?
4. What would happen to a cell if it we were to freeze the spindle fibers of all cells?
Meiosis
 Discuss with your partner the difference in sister chromatids and homologous chromosomes. Be ready to
show me the difference in the two with your chromosome beads.
 We will now model meiosis.
o Prophase I
 Model your cell in prophase I. Use the terms synapse, tetrad, crossing over, and
chiasmata. Also, include 2 similarities and 2 differences in prophase I of meiosis and
prophase of mitosis that we have just modeled.
 How does crossing over in this stage increases genetic variation?
o Metaphase I
 Model your cell in metaphase I. We know metaphase means middle. Write the name of
the structure that is in the middle now as well as the name of the structure that goes to the
middle during metaphase of mitosis.
 Use your chromosome bead set to model the Law of Independent Assortment. How does
this increase genetic variation?
o Anaphase I
 Model your cell in anaphase I. How many chromosomes are present in the cell now?
How does this compare to the number of chromosomes present during anaphase of
mitosis?
 Use your chromosome bead set to model the Law of Segregation. How does this increase
genetic variation?
o

Telophase I
 Model your cells in telophase I. Describe how you know that these cells are now haploid
instead of diploid.
o Meiosis II is just like mitosis except the cells now have half the chromosomes because they are
haploid. Work through PMAT II to show your understanding of these stages.
o At the end of Meiosis II, you have now created either 4 functional haploid gametes or 1 functional
haploid egg (the other 3 cells are called polar bodies and will not be used). What is random
fertilization, and how does this increase genetic variation?
Purpose of meiosis. Discuss with your partner each of the following questions.
o What are some differences between the processes of mitosis and meiosis that you have just
modeled?
o What type of cells undergoes meiosis?
o Why do these cells use meiosis to reproduce while all other cells use mitosis? (Hint: Think of the
difference in haploid and diploid. Why would some cells want to be haploid while all other are
diploid?)
o Meiosis increases genetic variation in 4 different ways. What are these, and how does each
increase genetic variation? (Hint: Three of them are while the cells are being made and 1 of them
after).
 What is the benefit of having genetic variation in a population?