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1. Lab 9: Meiosis Prelab 9 and the Lab report is due.
Lab 8 is due by the end of the class. (You may work on the 1st part in lab today. Make sure you turn it in or it is late.)
Microworlds is due NEXT CLASS – you should have tons of time to work on it today
2. Chromosomes
3. Mitosis makes cells, but what about making babies? Does Mitosis produce gametes (sex cells: egg and sperm)?
4. Meiosis Resembles 2 rounds of mitosis
2 cell divisions (meiosis I and meiosis II)
4 resulting haploid cells
5. Meiosis
6. Meiosis I: Prophase I Chromosomes condense
Homologous chromosomes (homologues) pair up
Crossing over occurs
Nuclear membrane degrades
7. Meiosis I: Metaphase I Spindle fibers attach to centromeres
Homologues line up on equator (metaphase plate)
8. Meiosis I: Anaphase I Homologues separate (each still consists of two sister chromatids)
Chromosome # halves (counting centromeres)
9. Meiosis I: Telophase I Nuclear membranes reforms
Cytokinesis follows
Haploid cells as the homologs split not the sister chromatids
10. Meiosis II: Prophase II Chromosomes condense again
Nuclear membrane breaks down
2 sister chromatids to 1 chromosome
11. Meiosis II: Metaphase II Spindle fibers attach to centromeres
Chromosomes line up on the metaphase plate
This only looks as shown when viewed from the equator, it looks like a mess when viewed from the poles.
12. Meiosis II: Anaphase II Sister chromatids separate and move to opposite plates
The microtubules contract, moving the chromatids
13. Meiosis II: Telophase II Nuclear membranes reforms
Chromosomes unwrap
Cytokinesis follows
4 haploid cells produced (at least in males, we’ll skip the more complicated oogenesis)
14. Modeling Meiosis with Play-doh Make a diploid cell with 3 chromosomes of different sizes.
Be sure to model all the steps in meiosis
One of the exercises models crossing over
15. Rest of Lab If needed, finish the protein synthesis part of Lab 8. Turn it in before you go.
Work on your Microworlds project, it is due next week. (Slides and pond water available.)
When you are all done, you are free to go!