1. Cell Cycle Repeating cycle of growth and division
Interphase—takes up ~ 80% of cell’s life; 3 phases
G1—cell is rapidly growing and carrying out routine functions (longest)
S—synthesis phase when DNA replicates from a single chromatid into a full chromosome
G2—organelles replicate and chemicals needed for mitosis are produced and sent to proper locations within the cell

2. Cell Division and Mitosis
When a cell becomes too large to function properly due to surface area-to-volume ratio it will be stimulated to divide
Prokaryotic cells (bacteria) undergo binary fission: asexual reproduction that produces identical daughter cells
Can occur every 20 minutes!!
First the single circular strand of DNA replicates, then the cell divides into 2 cells that are identical in every way—think “cloning”!

3. Eukaryotic Mitosis and Cell Division
Due to all the organelles in eukaryotes, process more complex
Mitosis—nuclear division—nucleus divides into 2 identical nuclei; made of 4 phases
Replaces old cells in an organism
Replaces damaged cells
Remembered by the acronym: PMAT
Occurs only in somatic cells—gametes are a whole another process!

4. P = Prophase
Chromosomes begin to condense into fuzzy X’s and are visible under a light microscope
Nuclear membrane starts to dissolve
Centrioles start to move apart to opposite sides of cell
Spindle fibers (protein microtubules) form between centrioles—these fibers help pull the chromosomes apart later
Plants do not have centrioles, but they do have spindle fibers

5. M = Metaphase
Second set of spindle fibers extend out from each chromosome’s centromere—2, one in each centriole direction
Grow until they reach the first set of spindle fibers
Spindle fibers line the chromosomes up at the center (equator) of the cell

6. A= Anaphase Centromeres divide and the 2 chromatids separate
Spindle fibers shorten and the chromatids move toward opposite sides of the cell
Looks like centrioles are reeling them in as if fishing!

7. T = Telophase
Chromatids undergo name change and are now called chromosomes again
Chromosomes start to uncoil at opposite sides of cell
New nuclear membranes form around them
Spindle fibers break and dissolve

8. Cytokinesis
Cell then starts to divide: cytoplasm is split into 2 new cells
In animals a cleavage furrow forms between the nuclei—cytoplasm is pinched in half
In plants vesicles (created by Golgi bodies) fuse at center of the cell and form a cell plate
New cell wall is created on either side of the plate
In both plants and animals, the 2 new cells each have their own organelles (formed during G2)