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AP Biology Chapter 12: The Cell Cycle. One cell becoming two.

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Presentation on theme: "AP Biology Chapter 12: The Cell Cycle. One cell becoming two."— Presentation transcript:

1 AP Biology Chapter 12: The Cell Cycle

2 One cell becoming two

3 Chromatin vs. Chromosomes appearance within the cell.

4 Fig: 19.4 Coiling up of Chromatin

5 Somatic cells vs. Germ cells The egg surrounded by sperm.

6 Fig: 12.4 Before and after the S phase

7 Mitosis (1 Division) vs. Meiosis (2 Divisions)

8 Interphase

9 Interphase cell (Look at the chromatin in the blue nucleus and the yellow cytoskeleton.)

10 Fig: 12.6 a

11 Cell in Prophase

12 Fig: 12.6 b

13 Cell in Metaphase

14 Cell in Anaphase

15 Cell in Telophase and starting Cytokinesis

16 LE 12-8b Chromosome movement Microtubule Motor protein Chromosome Kinetochore Tubulin subunits

17 Animal vs. Plant

18 LE Nucleus Cell plate Chromosomes Nucleolus Chromatin condensing 10 µm Prophase. The chromatin is condensing. The nucleolus is beginning to disappear. Although not yet visible in the micrograph, the mitotic spindle is starting to form. Prometaphase. We now see discrete chromosomes; each consists of two identical sister chromatids. Later in prometaphase, the nuclear envelope will fragment. Metaphase. The spindle is complete, and the chromosomes, attached to microtubules at their kinetochores, are all at the metaphase plate. Anaphase. The chromatids of each chromosome have separated, and the daughter chromosomes are moving to the ends of the cell as their kinetochore micro- tubules shorten. Telophase. Daughter nuclei are forming. Meanwhile, cytokinesis has started: The cell plate, which will divide the cytoplasm in two, is growing toward the perimeter of the parent cell.

19 Microscopic view of Mitosis in Onion root tips. Can you identify the stages?

20 LE 12-11_3 Origin of replication Cell wall Plasma membrane Bacterial chromosome E. coli cell Two copies of origin Chromosome replication begins. Soon thereafter, one copy of the origin moves rapidly toward the other end of the cell. Replication continues. One copy of the origin is now at each end of the cell. Origin Replication finishes. The plasma membrane grows inward, and new cell wall is deposited. Two daughter cells result.

21 Checkpoints (Is all going according to plan?)

22 LE G1G1 G 1 checkpoint G1G1 G0G0 If a cell receives a go-ahead signal at the G 1 checkpoint, the cell continues on in the cell cycle. If a cell does not receive a go-ahead signal at the G 1 checkpoint, the cell exits the cell cycle and goes into G 0, a nondividing state.

23 LE 12-16a MPF activity G1G1 G2G2 S MS M G2G2 G1G1 M Cyclin Time Fluctuation of MPF activity and cyclin concentration during the cell cycle Relative concentration

24 LE 12-16b Degraded cyclin G 2 checkpoint S M G2G2 G1G1 Cdk Cyclin is degraded MPF Cyclin Cdk Molecular mechanisms that help regulate the cell cycle accumulation Cyclin

25 LE 12-8b Chromosome movement Microtubule Motor protein Chromosome Kinetochore Tubulin subunits

26 LE 12-18a Cells anchor to dish surface and divide (anchorage dependence). When cells have formed a complete single layer, they stop dividing (density-dependent inhibition). If some cells are scraped away, the remaining cells divide to fill the gap and then stop (density-dependent inhibition). 25 µm Normal mammalian cells

27 LE 12-18b Cancer cells do not exhibit anchorage dependence or density-dependent inhibition. Cancer cells 25 µm

28 Malignant cancer cells from the breast (See the ABNORMAL crab shape of the cells.)


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