Section 4-3Cell 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).
Spindle Fibers
Centromere
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.
Cell Cycle Quick Draw