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