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Section 4-3. Cell Division. The Cell Cycle. During the cell cycle a cell grows, prepares for division, and divides into two “daughter cells”. Stage 1: Interphase. The cell grows, duplicates organelles, and makes a copy of DNA. The cell’s nucleus is uniform and the cell is regularly shaped
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Section 4-3 Cell Division
The Cell Cycle • During the cell cycle a cell grows, prepares for division, and divides into two “daughter cells”
Stage 1: Interphase • The cell grows, duplicates organelles, and makes a copy of DNA. • The cell’s nucleus is uniform and the cell is regularly shaped • It just looks like a cell…
Stage 2: Mitosis • The nucleus of the cell divides into two new nuclei • Mitosis has 4 stages • By looking at the nucleus and chromosomes you can determine what stage of mitosis the cell is in.
Mitosis 1: Prophase • During prophase the chromatin (bundles of DNA) condense into two-rod structures called chromosomes, which makes the nucleus look chunky • There are two rods in chromosomes because DNA has been duplicated.
Mitosis 2: Metaphase • During metaphase the chromosomes line up down the middle of the cell. • They are attached to the centrioles by spindle fibers (used to be the cytoskeleton). Centromere Spindle Fibers
Mitosis 3: Anaphase • During anaphase the chromosomes are torn apart at the centromeres and move toward opposite ends of the cell.
Mitosis 4: Telophase • During telophase the chromosomes begin to lose their rod-shape and a new nucleus starts to form around them.
Stage 3: Cytokinesis • The cell membrane pinches off and the cell splits in two. • Called daughter cells • The new cells are now in interphase and the cycle starts again.