c ell c ycle dr. brasington. s omatic cell division the process of a cell dividing into 2 identical...
TRANSCRIPT
CELL CYCLEDr. Brasington
SOMATIC CELL DIVISION
The process of a cell dividing into 2 identical daughter cells.
Occurs when cells reach a certain age A means of body growth, replacing older
cells, and repairing injured parts of the body. 3 stages: interphase, mitosis, and
cytokinesis.
INTERPHASE
Cells spend most of their time in interphase. Subdivided into G1, S, G2. G0? G1: Cell grows larger S: Chromosomes are duplicated and the
amount of DNA doubles. G2: More growth and cell prepares for
mitosis. Mitosis: The division of the nucleus to
produce 2 diploid nuclei. -Occurs at the END of interphase.
PHASES OF MITOSIS
Prophase Metaphase Anaphase Telophase
PROPHASE
The nuclear membrane disappears. The spindle apparatus begins to form. The chromosomes (comprised of 2 sister
chromatids)condense .
PROPHASE
METAPHASE
Chromosomes line up at the equator at the metaphase plate.
Centrioles align at opposite poles. Microtubules that make up the spindle fibers
extend from the poles to the center of the cell.
Chromosomes move randomly until they attach at their kinetochores to polar fibers from both sides of their centromeres.
Kinetochores: Protein structure where spindle fibers attach to pull sister chromatids apart.
METAPHASE
METAPHASE
ANAPHASE The paired centromeres begin to move apart. Once the paired sister chromatids separate from
one another, each is considered a “full” chromosome “daughter chromosomes”.
Through the spindle apparatus, the daughter chromosomes move to the poles at opposite ends of the cell.
The 2 poles of the cell also begin to move apart. At the end of anaphase, each pole has a complete
compilation of chromosomes.
ANAPHASE
ANAPHASE
ANAPHASE
TELOPHASE
Nuclei begin to form at opposite poles. Nuclear envelopes are formed . Nucleoli reappear. Chromatin fibers of the chromosomes uncoil. Spindle fibers and centrioles disappear. Cytokinesis. Completion of the cycle marks beginning of
life cycle for the 2 daughters. Life cycle ends when the 2 daughters divide again.
TELOPHASE
TELOPHASE
THE END