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M phase. DNA at different phases chromatin chromosome histone nucleosome.

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Presentation on theme: "M phase. DNA at different phases chromatin chromosome histone nucleosome."— Presentation transcript:

1 M phase

2 DNA at different phases chromatin chromosome histone nucleosome

3 DNA at different phases Chromatin - DNA + protein - before cell division (M phase) Chromosome - condensed chromatin during cell division Sister Chromatid - each individual double helix

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9 FYI.. Body cells (autosomes/somatic cells) have 46 chromosomes or 23 pairs – Diploid – 2n Sex cells (gametes) have 23 chromosomes – Haploid - n

10 M phase Mitosis (nuclear division) Cytokinesis (cytoplasmic division)

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12 Mitosis Nuclear division Cell growth stops Produces 2 similar daughter cells (2n) Asexual reproduction 1-2 hrs only Metaphase Checkpoint

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14 Stages of Mitosis Prophase Metaphase Anaphase Telophase Cytokinesis

15 Prophase Chromatin thickens into chromosomes Nuclear membrane and nucleolus disintegrates Mitotic spindle forms Centrosome pairs move to opposite ends

16 Prophase

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18 Metaphase

19 Chromosomes at metaphase plate Centrosomes at opposite poles Kinetochores attached to microtubules

20 Secrets on how chromosomes move.. CentrosomeAster Sister chromatids Metaphase Plate Kinetochores Overlapping nonkinetochore microtubules Kinetochores microtubules Centrosome Chromosomes Microtubules 0.5 µm 1 µm Figure 12.7

21 Secrets.. Spindle pole Kinetochore

22 microtubule

23 Anaphase

24 Centromeres divide Chromatids now chromosomes Kinetochore microtubules shorten - Chromosomes separate and move Nonkinetochore microtubules lengthen End: chromosomes at 2 poles

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26 Motor protein

27 Telophase

28 Chromosomes arrive at opposite poles Spindle fibers disintegrate Nuclear membrane reforms & Nucleolus reappears Chromatin fibers become less tightly coiled

29 Cytokinesis

30 Cytoplasm divides Animals: cleavage furrow divides cytoplasm Plant cells: cell plate Two daughter cells

31 Cell pinches inward

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33 Daughter cells 1 µm Vesicles forming cell plate Wall of patent cell Cell plate New cell wall Cell Plate Formation

34 Mitosis in an Animal Cell

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36 Cleavage furrow Centrioles ANIMAL CELL

37 Cell plate No centrioles PLANT CELL

38 Result of Cell Cycle two new daughter cells – identical to the parent cell in chromosome number and chromosome type net gain of only one cell two new daughter cells will enter interphase and the cycle will continue…

39 Cell Cycle


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