100 µm

1. 20 µm 100 µm 200 µm (a) Reproduction (b) Growth and development (c) Tissue renewal

2. 20 µm

3. 0.5 µm Chromosomes DNA molecules Chromo- some arm Chromosome duplication (including DNA synthesis) Centromere Sister chromatids Separation of sister chromatids Centromere Sister chromatids

4. INTERPHASE S (DNA synthesis) G1 Cytokinesis G2 Mitosis MITOTIC (M) PHASE

5. Metaphase Anaphase Telophase and Cytokinesis G2 of Interphase Prophase Prometaphase Centrosomes (with centriole pairs) Early mitotic spindle Centromere Chromatin (duplicated) Fragments of nuclear envelope Nonkinetochore microtubules Aster Cleavage furrow Metaphase plate Nucleolus forming Daughter chromosomes Nuclear envelope forming Centrosome at one spindle pole Spindle Nuclear envelope Kinetochore Chromosome, consisting of two sister chromatids Kinetochore microtubule Plasma membrane Nucleolus

6. Aster Centrosome Sister chromatids Microtubules Chromosomes Metaphase plate Kineto- chores Centrosome 1 µm Overlapping nonkinetochore microtubules Kinetochore microtubules 0.5 µm

7. EXPERIMENT Kinetochore Spindle pole Mark RESULTS CONCLUSION Chromosome movement Kinetochore Tubulin subunits Motor protein Microtubule Chromosome

8. Vesicles forming cell plate Wall of parent cell 1 µm 100 µm Cleavage furrow Cell plate New cell wall Daughter cells Contractile ring of microfilaments Daughter cells (a) Cleavage of an animal cell (SEM) (b) Cell plate formation in a plant cell (TEM)

9. Nucleus Chromatin condensing 10 µm Chromosomes Cell plate Nucleolus 2 4 1 Prophase Prometaphase 3 Metaphase Anaphase Telophase 5

10. Cell wall Origin of replication Plasma membrane E. coli cell Bacterial chromosome Two copies of origin Origin Origin

11. Bacterial chromosome (a) Bacteria Chromosomes Microtubules Intact nuclear envelope (b) Dinoflagellates Kinetochore microtubule Intact nuclear envelope (c) Diatoms and yeasts Kinetochore microtubule Fragments of nuclear envelope (d) Most eukaryotes

12. EXPERIMENT Experiment 1 Experiment 2 G1 S G1 M RESULTS M S S M When a cell in the S phase was fused with a cell in G1, the G1 nucleus immediately entered the S phase—DNA was synthesized. When a cell in the M phase was fused with a cell in G1, the G1 nucleus immediately began mitosis—a spindle formed and chromatin condensed, even though the chromosome had not been duplicated.

13. G1 checkpoint Control system S G1 G2 M M checkpoint G2 checkpoint

14. G0 G1 checkpoint G1 G1 (b) Cell does not receive a go-ahead signal Cell receives a go-ahead signal

15. M M S G1 G1 M G1 S G2 G2 MPF activity Cyclin concentration Time (a) Fluctuation of MPF activity and cyclin concentration during the cell cycle S G1 Cdk Cyclin accumulation M Degraded cyclin G2 G2 Cdk checkpoint Cyclin is degraded Cyclin MPF (b) Molecular mechanisms that help regulate the cell cycle

16. Scalpels Petri plate Without PDGF cells fail to divide With PDGF cells prolifer- ate Cultured fibroblasts 10 µm

17. Anchorage dependence Density-dependent inhibition Density-dependent inhibition 25 µm 25 µm (a) Normal mammalian cells (b) Cancer cells

18. Lymph vessel Tumor Blood vessel Cancer cell Glandular tissue Metastatic tumor Cancer cells invade neigh- boring tissue. A tumor grows from a single cancer cell. Cancer cells spread to other parts of the body. Cancer cells may survive and establish a new tumor in another part of the body. 4 2 1 3