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Cell Division
Mitosis and Meiosis
The Cell Cycle
Cell Growth
 Prior to mitosis, the cell is in Interphase
Interphase is a time where
The cell grows
 Organelles replicate
 DNA is copied
 Most of a cells life is spent in interphase
 Occurs in body cells (somatic cells)
 Results in 2 daughter cells identical to the
parent cell
 4 phases: prophase, metaphase, anaphase,
and telophase
 Stage 1 of Mitosis
DNA winds up to form chromosomes
Nuclear membrane (membrane around the
nucleus) disappears
 Stage 2 of Mitosis
 Chromosomes line up at equator (center) of
the cell
 Stage 3 of Mitosis
 Chromosomes split - each half is pulled to
opposite sides of the cell
 Stage 4 of Mitosis
 Nuclear membranes form around each set of
chromosomes and the chromosomes unwind
to form strands of DNA
 After mitosis occurs, the cells must split this process is called cytokinesis
 There are two methods - one for cells without
a cell wall, like animal cells, and one for
cells with a cell wall, like plant cells
Cytokinesis - No Cell Wall
 The membrane starts to pinch inward,
between the two nuclei
 It will continue to pinch, until the cell splits
into two new cells
Cytokinesis - Cell Wall
 Cell forms a cell plate between the two
 This cell plate provides foundation for new
cell wall
 Membranes form inside cell walls, and end
up with two daughter cells
Meiosis - Formation of Sex
 Occurs in sex cells (eggs and sperm)
 Results in 4 daughter cells
Each with HALF the DNA of the parent cell
All are different from one another AND parent
 Split into two Stages, each with 4 phases
Prophase I
 DNA winds up into chromosomes
 Nuclear membrane disappears
Metaphase I
 Chromosomes line up at equator
 Line up next to homogolous chromosome
(e.g. chromosome 1 from dad lines up next to
chromosome 1 from mom)
Anaphase I
 One chromosome from each pair is pulled to
opposite sides of the cell
Telophase I & Cytokinesis
 Nuclear membrane forms around each set of
 Chromosomes may unwind
 Cells split
Prophase II
 Nuclear membrane disappears
 Chromosomes wind up
Metaphase II
 Chromosomes line up at equator
Anaphase II
 Chromosomes split, each half pulled to
opposite sides of the cell
Telophase II & Cytokinesis
 Nuclear membrane reforms around each set
of chromosomes
 Chromosomes unwind
 Cells split
Compare Mitosis/Meiosis
4 cells formed
2 cells formed
Daughter cells have 1/2
Daughter cells identical to Prophase
Metaphase DNA of the parent cell
parent cell
Occurs in body cells
4 phases
Cells divide
All 4 are different
Occurs in sex cells
8 phases/2 stages