1. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh Edition Solomon Berg Martin Chapter 9 Chromosomes, Mitosis, and Meiosis

2. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 9 Chromosomes, Mitosis, and Meiosis Cells Basic unit of life Essential link between generations Genomes –Even simplest cell contains DNA, collectively called the organism’s genome –Organized into genes

3. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 9 Chromosomes, Mitosis, and Meiosis Prokaryotic cells Circular DNA molecules Eukaryotic cells Chromosome packaging facilitated by histones Histones form nucleosomes Scaffolding proteins maintain chromosome structure

4. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 9 Chromosomes, Mitosis, and Meiosis Nucleosomes

5. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 9 Chromosomes, Mitosis, and Meiosis Mouse metaphase chromosome depleted of histones

6. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 9 Chromosomes, Mitosis, and Meiosis Eukaryotic cell cycle Beginning of one division to beginning of next Stages in eukaryotic cell cycle Interphase –First gap phase –Synthesis phase –Second gap phase M phase –Mitosis –Cytokinesis

7. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 9 Chromosomes, Mitosis, and Meiosis Eukaryotic cell cycle

8. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 9 Chromosomes, Mitosis, and Meiosis Structure of duplicated chromosome Pair of sister chromatids –Contain identical DNA sequences –Tightly associated in region of centromeres Each chromatid –Includes region called centromere –Kinetochore attached to each centromere

9. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 9 Chromosomes, Mitosis, and Meiosis Mitosis Identical chromosomes distributed to each cell pole and a nuclear envelope forms Stages –Prophase –Metaphase –Anaphase –Telophase

10. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 9 Chromosomes, Mitosis, and Meiosis Stages of Mitosis

11. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 9 Chromosomes, Mitosis, and Meiosis Asexual reproduction Offspring have hereditary traits identical to single parent Mitosis is basis Sexual reproduction Gametes fuse to form a zygote Meiosis is basis

12. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 9 Chromosomes, Mitosis, and Meiosis Diploid cells Characteristic number of chromosome pairs per cell –Homologous chromosomes –Similar in length, shape, other features, and carry similar attributes Haploid cells Contain only one member of each homologous chromosome pair

13. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 9 Chromosomes, Mitosis, and Meiosis Meiosis Diploid cell undergoing meiosis yields four haploid cells

14. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 9 Chromosomes, Mitosis, and Meiosis Stages of Meiosis

15. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 9 Chromosomes, Mitosis, and Meiosis Meiosis in the trumpet lily

16. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 9 Chromosomes, Mitosis, and Meiosis Meiotic tetrad with two chiasmata

17. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 9 Chromosomes, Mitosis, and Meiosis Mitosis Prophase Anaphase Daughter cells Mitosis vs. Meiosis Meiosis Prophase I Anaphase I Prophase II Anaphase II Haploid cells

18. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 9 Chromosomes, Mitosis, and Meiosis Mitosis and meiosis

19. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 9 Chromosomes, Mitosis, and Meiosis Roles of mitosis and meiosis in various life cycles Many simple eukaryotes remain haploid In sexual life cycle, meiosis occurs before gametes form Plants, some algae, and some fungi have complex life cycles with alternation of generations

20. Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 9 Chromosomes, Mitosis, and Meiosis Representative life cycles