<p> 100 µm 200 µm 20 µm </p><p>(a) Reproduction (b) Growth and (c) Tissue renewal development </p><p>20 µm </p><p>1 2 </p><p>0.5 µm <a href="/tags/Chromosome/" rel="tag">Chromosomes</a> DNA molecules </p><p>Chromo- <a href="/tags/Chromosome/" rel="tag">Chromosome</a> some arm duplication (including DNA S synthesis) G1 Centromere (DNA synthesis) </p><p>Sister chromatids G2 <a href="/tags/Cytokinesis/" rel="tag">Cytokinesis</a> MITOTIC <a href="/tags/Mitosis/" rel="tag">Mitosis</a> Separation of (M) PHASE sister chromatids </p><p>Centromere </p><p>Sister chromatids 3 4 </p><p>Aster <a href="/tags/Centrosome/" rel="tag">Centrosome</a> Sister chromatids Microtubules Chromosomes <a href="/tags/Metaphase/" rel="tag">Metaphase</a> plate </p><p>G of <a href="/tags/Interphase/" rel="tag">Interphase</a> <a href="/tags/Prophase/" rel="tag">Prophase</a> Metaphase <a href="/tags/Anaphase/" rel="tag">Anaphase</a> <a href="/tags/Telophase/" rel="tag">Telophase</a> and Cytokinesis 2 <a href="/tags/Prometaphase/" rel="tag">Prometaphase</a> Kineto- <a href="/tags/Centrosome/" rel="tag">Centrosomes</a> Chromatin Early mitotic Aster Centromere Fragments Nonkinetochore Metaphase Cleavage Nucleolus chores (with centriole (duplicated) spindle of nuclear microtubules plate furrow forming pairs) envelope </p><p>Centrosome 1 µm </p><p>Daughter Nuclear Nucleolus Nuclear Plasma Chromosome, consisting <a href="/tags/Kinetochore/" rel="tag">Kinetochore</a> Kinetochore Spindle Centrosome at chromosomes one spindle pole envelope Overlapping envelope membrane of two sister chromatids microtubule forming nonkinetochore Kinetochore microtubules microtubules </p><p>0.5 µm 5 6 EXPERIMENT Kinetochore </p><p>Spindle pole </p><p>Mark </p><p>RESULTS Vesicles Wall of 1 µm 100 µm forming parent cell Cleavage furrow cell plate Cell plate New cell wall </p><p>CONCLUSION Contractile ring of Daughter cells Chromosome microfilaments Daughter cells movement (a) Cleavage of an animal cell (SEM) (b) Cell plate formation in a plant cell (TEM) Kinetochore </p><p>Motor Tubulin Microtubule <a href="/tags/Protein/" rel="tag">protein</a> subunits Chromosome 7 8 </p><p>Cell wall <a href="/tags/Origin_of_replication/" rel="tag">Origin of replication</a> Plasma membrane E. coli cell Bacterial Two copies chromosome of origin Nucleus Chromatin 10 µm Nucleolus condensing Chromosomes Cell plate </p><p>Origin Origin </p><p>1 Prophase 2 Prometaphase 3 Metaphase 4 Anaphase 5 Telophase </p><p>9 10 </p><p>Bacterial chromosome EXPERIMENT Experiment 1 Experiment 2 (a) Bacteria </p><p>Chromosomes </p><p>Microtubules S G1 M G1 </p><p>Intact nuclear RESULTS envelope (b) Dinoflagellates </p><p>Kinetochore microtubule S S M M Intact nuclear envelope When a cell in the When a cell in the (c) Diatoms and yeasts S phase was fused M phase was fused with with a cell in G1, the G1 a cell in G1, the G1 Kinetochore nucleus immediately nucleus immediately microtubule entered the S began mitosis—a phase—DNA was spindle formed and synthesized. chromatin condensed, Fragments of even though the nuclear envelope chromosome had not (d) Most eukaryotes been duplicated. 11 12 G1 checkpoint </p><p>G0 G checkpoint Control 1 system S G1 </p><p>M G2 G1 G1 </p><p>(a) Cell receives a go-ahead (b) Cell does not receive a signal go-ahead signal M checkpoint </p><p>G2 checkpoint 13 14 </p><p>M G1 S G2 M G1 S G2 M G1 </p><p>MPF activity <a href="/tags/Cyclin/" rel="tag">Cyclin</a> concentration Scalpels </p><p>Time (a) Fluctuation of MPF activity and cyclin concentration during the <a href="/tags/Cell_cycle/" rel="tag">cell cycle</a> Petri plate </p><p>S Cyclin accumulation G 1</p><p>Cdk Without PDGF With PDGF M </p><p>Degraded G 2 cells fail to divide cells prolifer- cyclin ate G2 Cdk Cyclin is checkpoint degraded Cultured fibroblasts 10 µm Cyclin MPF </p><p>(b) Molecular mechanisms that help regulate the cell cycle 15 16 </p><p>Anchorage dependence </p><p>Lymph Density-dependent inhibition vessel Tumor Blood vessel </p><p>Density-dependent inhibition Cancer Glandular cell tissue Metastatic tumor 1 A tumor grows 2 Cancer cells 3 Cancer cells spread 4 Cancer cells may from a single invade neigh- to other parts of survive and cancer cell. boring tissue. the body. establish a new tumor in another part of the body. 25 µm 25 µm </p><p>(a) Normal mammalian cells (b) Cancer cells </p><p>17 18 </p>