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10.2 Eukaryotic Cell Cycle Cell cycle--repeating phases of : –Growth (Interphase) –DNA replication (Interphase) –preparation for cell division (Interphase) –division of the nucleus and cytoplasm (cell division—mitosis & cytokinesis)

Interphase G 1 : cell grows to mature size, makes more organelles S: chromosomes replicate G 2 : cell continues to grow and prepare to divide; cell forms specialized structures that help the cell divide (ex. microtubules)

2 Stages of Cell Division: 1.Mitosis: the process in which a cell’s nucleus divides into 2 identical daughter nuclei. *Begins after interphase and ends before cytokinesis. *PMAT (4 phases) 2.Cytokinesis: cytoplasm division (and organelles) *Cell physically splits into 2

MITOSIS — 4 phases (PMAT): 1. PROPHASE chromosomes condense (coil up and become visible under a microscope). Centrosome helps to assemble spindle fibers. a pair of centrioles migrate to each pole of the cell (animal cells only). nuclear envelope and nucleolus break down (disappear).

2. METAPHASE spindle fibers arrange chromosomes in the middle of the cell along the equator of the cell. spindle fibers link the chromatids of each chromosome to opposite poles.

3. ANAPHASE centromeres divide spindle fibers pull sister chromatids towards opposite poles. result =each pole has a full set of chromosomes.

4. TELOPHASE 2 daughter nuclei are formed reverse of prophase: nuclear envelopes form around each set of chromosomes; chromosomes uncoil to form a loose mass of chromatin; spindle fibers break down (disappear).

CYTOKINESIS animal cell…cell membrane grows into the center of the cell at the center of the parent cell and divides it into 2 daughter cells of equal size; called a cleavage furrow plant cells…form a cell plate (from the parent cell wall).