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M phase.

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Presentation on theme: "M phase."— Presentation transcript:

1 M phase

2 DNA at different phases
histone nucleosome chromatin chromosome

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






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)


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


14 Stages of Mitosis Metaphase Prophase Anaphase Cytokinesis Telophase

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

16 Prophase

17 Prophase

18 Metaphase

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

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

21 Secrets.. Kinetochore Spindle pole

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


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


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

34 Mitosis in an Animal Cell


36 Cleavage furrow Centrioles ANIMAL CELL

37 Cell plate No centrioles PLANT CELL

38 Result of Cell Cycle two new daughter cells net gain of only one cell
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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