Cell Growth and Division The Cell Cycle Mitosis

Cell Growth and Division The Cell Cycle & Mitosis

¿ Are cells always dividing? ®Sometimes they are growing ®Sometimes they are preparing ®Sometimes they are dividing to divide

Cell Division = Mitosis ® During life, we go from one cell to ~ 75 trillion cells. ® Mitosis = division of body cells ® Cancer = uncontrolled cell division

Cells that rarely divide ® Mature skeletal muscle cells ® Nerve cells

Cells that constantly divide Skin cells ® Cells that line gastro-intestinal tract ®

Cell cycle ®= Period of time between one cell division & the next

Cell cycle – Phases I. Interphase G 1 - rapid cell growth - basic cell f(x)s

I. Interphase S = Synthesis – DNA replication G 2 = Organelles & cytosol made G 1 S G 2

Cell cycle - Phases II. Mitosis = cell division III. Cytokinesis = cytoplasm division ? s 1 -7

Sequence of Cell Cycle ®Interphase ®Prophase ®Metaphase ®Anaphase ®Telophase

Mitosis Includes : ®Prophase ®Metaphase ®Anaphase ®Telophase ®Cytokinesis (division of cytoplasm)

Cell during Interphase : ® DNA in form of chromatin ® Looks like hair / spaghetti (chrs. * not visible) * chromosomes

Prophase ® Chrs. coil and become visible ® Sister chromatids move towards poles ® Spindle forms ® Nuclear envelope & nucleoli disappear

Metaphase ® Sister chromatids line up at equator on metaphase plate (Meet me in the middle)

Anaphase ® Centromeres divide, chromatids split ® Sister chromatids move to opposite poles (centrioles) (Run away, run away!)

Telophase ® Chrs. uncoil and become invisible (now in form of chromatin) ® Spindle disappears ® Nuclear envelope & nucleoli re-appear

Cytokinesis ® Division into two identical DAUGHTER CELLS ® Starts during Telophase ® Finishes after Telophase is over animation

Whitefish cells during mitosis ? s 8 -15