Chapter 12Overview: The Key Roles of Cell DivisionSlide 3Slide 4LE 12-2Concept 12.1: Cell division results in genetically identical daughter cellsCellular Organization of the Genetic MaterialSlide 8LE 12-3Distribution of Chromosomes During Cell DivisionLE 12-4Slide 12Concept 12.2: The mitotic phase alternates with interphase in the cell cyclePhases of the Cell CycleLE 12-5Slide 16Slide 17LE 12-6caLE 12-6daSlide 20Check these web sites:The Mitotic Spindle: A Closer LookSlide 23LE 12-7Slide 25LE 12-8bSlide 27Cytokinesis: A Closer LookLE 12-9aLE 12-9bLE 12-10Binary FissionLE 12-11_1LE 12-11_2LE 12-11_3The Evolution of MitosisLE 12-12Concept 12.3: The cell cycle is regulated by a molecular control systemEvidence for Cytoplasmic SignalsLE 12-13The Cell Cycle Control SystemLE 12-14Slide 43LE 12-15The Cell Cycle Clock: Cyclins and Cyclin-Dependent KinasesLE 12-16aLE 12-16bStop and Go Signs: Internal and External Signals at the CheckpointsSlide 49LE 12-17Slide 51LE 12-18aRegulation of the Cell CycleSlide 54LE 12-18bLoss of Cell Cycle Controls in Cancer CellstumorsWhat is a metastasis?LE 12-19Web sites about cancer:Comparison of mitosis and meiosisFACTORS THAT CONTRIBUTE TO GENETIC VARIATION MUTATIONS CROSSING OVER DURING PROPHASE I OF MEIOSIS INDEPENDENT ASSORTMENT OF CHROMOSOMES during meiosis RANDOM FERTILIZATION OF THE EGG BY SPERM - Slide 63Copyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsPowerPoint Lectures for Biology, Seventh EditionNeil Campbell and Jane ReeceLectures by Chris RomeroChapter 12Chapter 12The Cell CycleCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsOverview: The Key Roles of Cell Division•The ability of organisms to reproduce best distinguishes living things from nonliving matter•The continuity of life is based upon the reproduction of cells, or cell divisionCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsCopyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings•In unicellular organisms, division of one cell reproduces the entire organism•Multicellular organisms depend on cell division for:–Development from a fertilized cell–Growth–Repair•Cell division is an integral part of the cell cycle, the life of a cell from formation to its own divisionLE 12-2LE 12-2Reproduction100 µmTissue renewalGrowth and development20 µm200 µmCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsConcept 12.1: Cell division results in genetically identical daughter cells•Cells duplicate their genetic material before they divide, ensuring that each daughter cell receives an exact copy of the genetic material, DNA•A dividing cell duplicates its DNA, allocates the two copies to opposite ends of the cell, and only then splits into daughter cellsCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsCellular Organization of the Genetic Material•A cell’s endowment of DNA (its genetic information) is called its genome•DNA molecules in a cell are packaged into chromosomesCopyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings•Every eukaryotic species has a characteristic number of chromosomes in each cell nucleus•Somatic (nonreproductive) cells have two sets of chromosomes•Gametes (reproductive cells: sperm and eggs) have half as many chromosomes as somatic cells•Eukaryotic chromosomes consist of chromatin, a complex of DNA and protein that condenses during cell divisionLE 12-3LE 12-325 µmCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsDistribution of Chromosomes During Cell Division•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 attachedLE 12-4LE 12-4Chromosomeduplication(including DNAsynthesis)0.5 µmCentromereSisterchromatidsSeparationof sisterchromatidsCentromeres Sister chromatidsCopyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings•Eukaryotic cell division consists of:–Mitosis, the division of the nucleus–Cytokinesis, the division of the cytoplasm•Gametes are produced by a variation of cell division called meiosis•Meiosis yields nonidentical daughter cells that have only one set of chromosomes, half as many as the parent cellCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsConcept 12.2: The mitotic phase alternates with interphase in the cell cycle•In 1882, the German anatomist Walther Flemming developed dyes to observe chromosomes during mitosis and cytokinesis•To Flemming, it appeared that the cell simply grew larger between one cell division and the next•Now we know that many critical events occur during this stage in a cell’s lifeCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsPhases of the Cell Cycle•The cell cycle consists of–Mitotic (M) phase (mitosis and cytokinesis)–Interphase (cell growth and copying of chromosomes in preparation for cell division)•Interphase (about 90% of the cell cycle) can be divided into subphases:–G1 phase (“first gap”)–S phase (“synthesis”)–G2 phase (“second gap”)LE 12-5LE 12-5G1G2S(DNA synthesis)INTERPHASECytokinesis MITOTIC(M) PHASEMitosisCopyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings•Mitosis is conventionally divided into five phases:–Prophase–Prometaphase–Metaphase–Anaphase–Telophase•Cytokinesis is well underway by late telophase[Animations and videos listed on slide following figure]Copyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsFig. 12.9LE 12-6caLE 12-6caG2 OF INTERPHASEPROPHASE PROMETAPHASELE 12-6daLE 12-6daMETAPHASEANAPHASETELOPHASE AND CYTOKINESIS10 µmCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsVideo: Animal MitosisVideo: Animal MitosisVideo: Sea Urchin (time lapse)Video: Sea Urchin (time lapse)Animation: Mitosis (All Phases)Animation: Mitosis (All Phases)Animation: Mitosis OverviewAnimation: Mitosis OverviewAnimation: Late Animation: Late InterphaseInterphaseAnimation: ProphaseAnimation: ProphaseAnimation: Animation: PrometaphasePrometaphaseAnimation: MetaphaseAnimation: MetaphaseAnimation: AnaphaseAnimation: AnaphaseAnimation: Animation:
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