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Phases of Mitosis and Meiosis: Understanding Cell Division

This chapter covers the duration of each phase of mitosis, corrections for Chapter 6, and introduces the stages of meiosis. Learn the differences between mitosis and meiosis and their significance in cell division. Includes a quote from Richard Bach on learning and winning.

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Phases of Mitosis and Meiosis: Understanding Cell Division

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  1. Hand in the Lab – How long is each phase of mitosis? and ALL chapter 6 corrections before the bell rings Chapter 6 Quiz 2 Begin Chapter 7 Stages of meiosis Meiosis vs. mitosis “That's what learning is, after all; not whether we lose the game, but how we lose and how we've changed because of it and what we take away from it that we never had before, to apply to other games. Losing, in a curious way, is winning.” Richard Bach To assess learning about Chapter 6 Title: Biology 1/10/07 Class Topics Objectives: Thursday, January 2, 20202:21 AM

  2. Class Assignments What By When • Lab – How long is each phase of mitosis? 1/10/07 • Chapter 6 Quiz 2 1/10/07 • Read 144-149 1/12/07 • W.S. 7.1 (DR/Quiz) 1/12/07 • Due this class period • Due next class period • Due in the future

  3. Grade Sheet

  4. Changes and Postquiz Activities • Changes • # 9 • option d • G0, G1, G2, G3 • #28 • Do not do • #35 • Instructions should state that the answers can be labeled with the phases of mitosis as well as interphase • Hand in when completed • Read 144-149

  5. Meiosis • Process of cell division - chromosome number is halved • From 2n to n • Formation of gametes • Starts after G1, S, G2 • Chromosomes have been replicated • Sister chromatids (4 arms) • Two divisions • Meiosis I, Meiosis II

  6. Meiosis: step by step • Meiosis I • Prophase I (same as mitosis except…) • The chromosomes pair up with their homolog (the other of the homologous pair) to form tetrads • during synapsis (pairing up), crossing over can occur

  7. Meiosis: step by step • Meiosis I • Metaphase I • homologous pairs line up along equator with spindle fibers attaching to only one side of each centromere • Anaphase I • The spindle fibers pull the homologous chromosomes to the separate poles • This gets the cell into the haploid state • Reduction division

  8. Meiosis: step by step • Meiosis I • Telophase I • Cytokinesis occurs and two haploid cells with sister chromatids have been formed • Meiosis II • Prophase II • Occurs right after telophase I has finished. No interphase between the two

  9. Meiosis: step by step • Meiosis II • Metaphase II • Haploid number of chromosomes line up along equator • Anaphase II • Sister chromatids separate • Telophase II • Cytokinesis occurs and cell enters interphase once more

  10. Mitosis no pairing of homologous chromosomes One division separation of chromatids Exact copy of original Diploid cells Meiosis homologous chromosomes paired form tetrads crossing over 2 divisions 1st reduction division 2nd separation of chromatids Haploid cells Mitosis vs Meiosis

  11. Meiosis: Totals • Four cells • All Haploid • Males - all usually develop completely • Spermatogenesis • Females - usually only 1 develops • Oogenesis

  12. From: http://www.accessexcellence.org/AB/GG/meiosis.html

  13. From: http://www.handsongenetics.com/meiosis.html

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