Chapter 12Figure 12.1 Chromosomes in a dividing cellFigure 12.2 The functions of cell divisionFigure 12.3 Eukaryotic chromosomesFigure 12.4 Chromosome duplication and distribution during cell divisionFigure 12.5 The cell cycleFigure 12.6 Exploring The Mitotic Division of an Animal CellSlide 8Slide 9Slide 10Figure 12.7 The mitotic spindle at metaphaseFigure 12.8 Inquiry During anaphase, do kinetochore microtubules shorten at their spindle pole ends or their kinetochore ends?Slide 13Slide 14Figure 12.9 Cytokinesis in animal and plant cellsFigure 12.10 Mitosis in a plant cellFigure 12.11 Bacterial cell division (binary fission)Figure 12.12 A hypothetical sequence for the evolution of mitosisFigure 12.13 Inquiry Are there molecular signals in the cytoplasm that regulate the cell cycle?Figure 12.14 Mechanical analogy for the cell cycle control systemFigure 12.15 The G1 checkpointFigure 12.16 Molecular control of the cell cycle at the G2 checkpointFigure 12.17 Inquiry Does platelet-derived growth factor (PDGF) stimulate the division of human fibroblast cells in culture?Slide 24Figure 12.18 Density-dependent inhibition and anchorage dependence of cell divisionFigure 12.19 The growth and metastasis of a malignant breast tumorUnnumbered Figure p. 235Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Copyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsPowerPoint TextEdit Art Slides for Biology, Seventh EditionNeil Campbell and Jane ReeceChapter 12Chapter 12The Cell CycleCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsFigure 12.1 Chromosomes in a dividing cellCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsFigure 12.2 The functions of cell division20 µm100 µm200 µm(a) Reproduction. An amoeba, a single-celled eukaryote, is dividing into two cells. Each new cell will be an individual organism (LM).(b) Growth and development. This micrograph shows a sand dollar embryo shortly after the fertilized egg divided, forming two cells (LM).(c) Tissue renewal. These dividing bone marrow cells (arrow) will give rise to new blood cells (LM).Copyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsFigure 12.3 Eukaryotic chromosomes50 µmCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsFigure 12.4 Chromosome duplication and distribution during cell division0.5 µmChromosomeduplication(including DNA synthesis)CentromereSeparation of sister chromatidsSisterchromatidsCentrometersSister chromatidsA eukaryotic cell has multiplechromosomes, one of which is represented here. Before duplication, each chromosomehas a single DNA molecule.Once duplicated, a chromosomeconsists of two sister chromatidsconnected at the centromere. Eachchromatid contains a copy of the DNA molecule.Mechanical processes separate the sister chromatids into two chromosomes and distribute them to two daughter cells.Copyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsFigure 12.5 The cell cycleINTERPHASEG1S(DNA synthesis)G2CytokinesisMitosisMITOTIC(M) PHASECopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsFigure 12.6 Exploring The Mitotic Division of an Animal CellG2 OF INTERPHASEPROPHASEPROMETAPHASECentrosomes(with centriole pairs)Chromatin(duplicated)Early mitoticspindleAsterCentromereFragmentsof nuclearenvelopeKinetochoreNucleolusNuclearenvelopePlasmamembraneChromosome, consistingof two sister chromatidsKinetochore microtubule NonkinetochoremicrotubulesCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsG2 of Interphase• A nuclear envelope bounds the nucleus.• The nucleus contains one or more nucleoli (singular, nucleolus).• Two centrosomes have formed by replication of a single centrosome.• In animal cells, each centrosome features two centrioles.• Chromosomes, duplicated during S phase, cannot be seen individually because they have not yet condensed.The light micrographs show dividing lung cells from a newt, which has 22 chromosomes in its somatic cells (chromosomes appear blue, microtubules green, intermediate filaments red). For simplicity, the drawings show only four chromosomes.Prophase• The chromatin fibers become more tightly coiled, condensing into discrete chromosomes observable with a light microscope.• The nucleoli disappear.• Each duplicated chromosome appears as two identical sister chromatids joined together.• The mitotic spindle begins to form. It is composed of the centrosomes and the microtubules that extend from them. The radial arrays of shorter microtubules that extend from the centrosomes are called asters (“stars”).• The centrosomes move away from each other, apparently propelled by the lengthening microtubules between them.Prometaphase• The nuclear envelope fragments.• The microtubules of the spindle can now invade the nuclear area and interact with the chromosomes, which have become even more condensed.• Microtubules extend from each centrosome toward the middle of the cell.• Each of the two chromatids of a chromosome now has a kinetochore, a specialized protein structure located at the centromere.• Some of the microtubules attach to the kinetochores, becoming “kinetochore microtubules.” These kinetochore microtubules jerk the chromosomes back and forth.• Nonkinetochore microtubules interact with those from the opposite pole of the spindle.Copyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsMETAPHASE ANAPHASE TELOPHASE AND CYTOKINESISSpindleMetaphaseplateNucleolusformingCleavagefurrowNuclear envelopeformingCentrosome at one spindle poleDaughter chromosomesCopyright © 2005 Pearson Education, Inc. publishing as Benjamin CummingsMetaphase• Metaphase is the longest stage of mitosis, lasting about 20 minutes.• The centrosomes are now at opposite ends of the cell. •The chromosomes convene on the metaphase plate, an imaginary plane that is equidistant between the spindle’s two poles. The chromosomes’ centromeres lie on the metaphase plate. • For each chromosome, the kinetochores of the sister chromatids are attached to kinetochore microtubules coming from opposite poles. • The entire apparatus of microtubules is called the spindle because of its