Chapter 12- The Cell Cycle

Chapter 12- The Cell Cycle - 1/31/2010 TheCellCycle 2010:...

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1/31/2010 1 The Cell Cycle © 2010: D. Julian Functions of cell division In unicellular organisms, division of one cell reproduces the entire organism. Multicellular organisms depend on cell division for: 1. Development from a fertilized cell 2. Growth 3. Repair Cell division is an integral part of the cell cycle the Cell division is an integral part of the cell cycle, the life of a cell from formation to its own division. In mitosis , cell division results in somatic daughter cells (nonreproductive cells) with identical DNA. In meiosis , cell division results in gamete daughter cells (reproductive cells: sperm and eggs) with nonidentical DNA. © 2010: D. Julian Cellular organization of DNA All the DNA in a cell constitutes the cell’s genome . A genome can consist of a single DNA molecule (common in prokaryotic cells) or a number of DNA molecules (common in eukaryotic cells). DNA molecules in a cell are packaged into chromosomes . © 2010: D. Julian
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1/31/2010 2 Chromosomes Every eukaryotic species has a characteristic number of chromosomes in each cell nucleus. Somatic cells have two sets of chromosomes. Gametes have half as many chromosomes as somatic cells. Eukaryotic chromosomes consist of chromatin , a complex of DNA and protein that condenses during cell division. © 2010: D. Julian Duplication and distribution of chromosomes In preparation for cell division, DNA is replicated and the chromosomes condense. Each duplicated chromosome has two sister chromatids , which separate during cell division. The centromere is the narrow “waist” of the duplicated chromosome, where the two chromatids are most closely attached. © 2010: D. Julian 0.5 μm Chromosomes Chromosome duplication (including DNA synthesis) Chromo- some arm Centromere DNA molecules Duplication and distribution of chromosomes Sister chromatids Separation of sister chromatids Centromere Sister chromatids © 2010: D. Julian
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1/31/2010 3 Phases of the cell cycle The cell cycle consists of: 1. Mitotic ( M )
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Chapter 12- The Cell Cycle - 1/31/2010 TheCellCycle 2010:...

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