(a) Reproduction. (b) Growth and development. (c) Tissue renewal

Transcription

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

2 20 µm 2

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

4 G 1 S (DNA synthesis) G 2 4

5 G 2 of Interphase Prophase Prometaphase Metaphase Anaphase Telophase and Cytokinesis Centrosomes Chromatin (with centriole (duplicated) pairs) Early mitotic spindle Aster Centromere Fragments of nuclear envelope Nonkinetochore microtubules Metaphase plate Cleavage furrow Nucleolus forming Nucleolus Nuclear Plasma envelope membrane Chromosome, consisting of two sister chromatids Kinetochore Kinetochore microtubule Spindle Centrosome at one spindle pole Daughter chromosomes Nuclear envelope forming 5

6 Aster Centrosome Microtubules Chromosomes Sister chromatids Metaphase plate Kinetochores Centrosome 1 µm Overlapping nonkinetochore microtubules Kinetochore microtubules 0.5 µm 6

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

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

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

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

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

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

13 G 1 checkpoint G 1 Control system S M G 2 M checkpoint G 2 checkpoint 13

14 G 0 G 1 checkpoint G 1 G 1 (a) Cell receives a go-ahead signal (b) Cell does not receive a go-ahead signal 14

15 M G 1 S G 2 M G 1 S G 2 M G 1 MPF activity Cyclin concentration Time (a) Fluctuation of MPF activity and cyclin concentration during the cell cycle Degraded cyclin Cyclin is degraded Cdk G 2 checkpoint Cdk Cyclin accumulation MPF Cyclin (b) Molecular mechanisms that help regulate the cell cycle 15

16 Scalpels Petri plate Without PDGF cells fail to divide With PDGF cells proliferate Cultured fibroblasts 10 µm 16

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

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