1. Clay Meiosis Make Up Instructions: Do the following in your lab book
Draw a picture at each phase that says
Make sure your phases show
spindles, centrioles, nucleus, and
cell membrane where appropriate.
Answer the questions as you go (six total).
Follow instructions on slide 20 to create a
baby Triffle!
Draw

2. Question 1: What will the haploid number of chromosomes be?
Observe the cellular events involved in Meiosis step by step using clay. These are the chromosomes of a Triffle, a mythical organism. The Triffle has a diploid chromosome number of four:
This means there are two pairs of homologous chromosomes. We call them chromosome 1 and chromosome 2
Question 1: What will the haploid number of chromosomes be?

3. Chromosome 1 and Chromosome 2: Homologous Pairs
Hi, Homie!!
Stop it. XD
Homologous pairs have the same genes in the same places.
Each pair has one chromosome from mom and one from dad.

4. Triffle Genes:
Blue
Pink
Brown b
Note that we are only looking at two genes on each chromosome, while ignoring hundreds of other genes.

5. Gene locations
The genes (alleles) are carved into the chromosomes so we can see when they are recombined during Meiosis.

6. DNA Replication during Interphase
During Interphase, each chromosome is replicated by DNA replication.
Draw
Q2) How many chromatids are present in the nucleus after DNA replication? How many chromosomes?

7. Prophase I: Crossing Over
Draw
Prophase I: Crossing Over
Now that homologous chromosomes are near each other, crossing over can occur.
In each tetrad, we trade one allele between two non-sister chromatids by first overlapping chromosome arms to form a cross over, and then joining the exchanged parts to create a new gene combination.

8. New gene combinations

9. Draw
Metaphase I:
Imagine that the nuclear membrane has now broken down in the Triffle cell, the spindle connected with the chromosomes, and the centrioles moved to opposite sides.
Now the homologous pairs are lined up in the middle of the cell, but the positions are random, so that the blue and green chromosome pair could switch places- called Independent Assortment. It’s the same for the brown and pink pair.

10. Metaphase I: Independent Assortment

11. Draw
Anaphase I:
Now each tetrad separates as the spindle fibers move them to opposite poles of the cell.

12. Telophase I and Cytokinesis
Draw
Telophase I and Cytokinesis
Spindle fibers disappear. Cytokinesis (cytoplasm division) occurs to form two daughter cells.
Q3: Could the blue chromosome have ended up in the cell with the pink chromosome?
Why?
Q4: Are the new cells haploid or diploid?

13. Telophase I and Cytokinesis
Spindle fibers disappear. Cytokinesis (cytoplasm division) occurs to form two daughter cells.
Q5: Are the two daughter cells identical (in genetic makeup)? Why or why not?

14. Prophase II
Draw
The chromosomes do not pair up this time since they were separated from their homologues, their “Homies!”
Later, Homie!
Miss you!

15. Metaphase II
Draw
The chromosomes in each cell line up end to end along the center line, and spindle fibers attach to their centromeres.

16. Anaphase 2
Draw
The two sister chromatids separate the spindle fibers to move them to opposite poles.
NOTICE how the steps in Meiosis II are very similar to MITOSIS!

17. Telophase 2 & Cytokinesis
Draw
Cytokinesis occurs again, producing a total of four daughter cells. C
Q6: Are the resulting cells haploid or diploid?

18. Telophase 2 & Cytokinesis
7) Write the genotypes (letters) for each of the resulting cells.

19. . After your gametes fuse together (combine your cells and the chromosomes in them), you have a zygote, which will develop into new offspring! Congratulations!
Draw
Your gamete
Baby Triffle
Gamete of a different Triffle
8) Write down the genotype of your new offspring! (All 8 letters of the combined gametes)

20. Draw
Finally:
9) Draw what the Triffle baby would look like (phenotype) using color for eyes and fur.
Use the gene information on slide 4