MITOTIC CELL DIVISION
ALL CELLS ARISE FROM OTHER CELLS BY CELL DIVISION. THIS PROCESS INVOLVES BOTH:
1) MITOSIS (duplication of the nucleus)
* this is an orderly series of complex changes in the nucleus
* this involves an EXACT DUPLICATION of the complete set of chromosomes
* also makes sure that these chromosomes are separated into two equal sets
* forms 2 cells identical to the first
2) CYTOPLASMIC DIVISION (cytokinesis)
* when the cytoplasm of the parent cell divides into 2 daughter cells
* also called cytokinesis
***When the process of cell division is uncontrolled, cells keep reproducing... which is called CANCER***
* Mitosis happens in all cells in humans EXCEPT eggs and sperm
CELL DIVISION
the process by which the nucleus of a cell divides, producing two nuclei with the diploid (2n--2 sets of chromosomes) number of chromosomes
I. INTERPHASE
* in between actual divisions
* the cell grows
* DNA exists as chromatin (a messy plate of spaghetti)
* the DNA duplicates (replicates) so now there are briefly 4 sets (4n); normally there are just 2 (2n)--one from each parent
* the centrioles also replicate (duplicate)
II. PROPHASE
* the DNA starts to condense and form chromosomes--the two halves of the chromosome (each chromatid) are held together at the centromere* the nuclear membrane that keeps the DNA (now in the form of chromosomes) in the nucleus starts to disappear
* the centrioles start to move towards different ends (or poles) of the cell
* the spindle apparatus (looks like a cage) forms from the framework of the cell around the centrioles (which now are look like stars called 'asters')
III. METAPHASE
* the spindle apparatus is fully formed and the chromosomes attach to it at the centromere
* the chromosomes line up in the middle of the spindle (called the metaphase plate)
IV. ANAPHASE
* the chromosomes separate at the centromere and split apart (chromosomes move away from each other)
* the spindle fibers shorten and pull the chromosomes to each end (aster)
V. TELOPHASE
* the chromosomes have finished moving to the different poles (ends) of the cell
* a new nuclear membrane starts to form around each new COMPLETE set of chromosomes
* the DNA starts to uncoil again to form chromatin
AT THIS POINT, ONLY THE NUCLEUS HAS DIVIDED INTO 2 IDENTICAL NUCLEI...WE STILL HAVE ONLY 1 CELL!
VI. CYTOPLASMIC DIVISION
* this make 2 daughter cells that are identical to the parent, but smaller!!
