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CELL CYCLE. Over time, many cells die and need to be replaced . Mitosis - The process by which a cell reproduces to create two identical cells. Daughter Cells - Two identical cells formed by mitosis
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CELL CYCLE Over time, many cells die and need to be replaced. • Mitosis - The process by which a cell reproduces to create two identical cells. • Daughter Cells - Two identical cells formed by mitosis • Cell Cycle – 4 different stages of the cell’s life leading to division into new daughter cells. • G1, S, G2, M • Many of the abnormal traits of cancer cells are due to defects in genes that control cell division.
Cell Cycle • The cell cycle consists of four stages G1, S, G2, and M. • G1 and G2 are 'gap' phases in which the cell grows and prepares to divide. • S in the synthesis phase in which the chromatin (DNA) is copied (replicated). • M is the mitotic phase in which the cell physically divides into two daughter cells. • Most cells are NOT actively dividing. These cells are in a resting state (G).
Mitosis is a process where cells are produced for growth and/or replacing damaged or old cells • Mitosis in normal cells produces two cells with identical genetic content. • Mitosis has four sub-phases:
PROPHASE • Chromosomes condense, the nuclear membrane breaks down, and spindle fibers form
METAPHASE • The replicated chromosomes line up in the middle of the cell
ANAPHASE • Chromosomes separate and the cell becomes elongated, with distinct ends (poles)
TELOPHASE • Nuclear envelopes re-form at the two poles and new cell membranes begin to form to create two independent cells
CYTOKINESISthe division of the cytoplasm to make two complete daughtercells • ANIMAL CELLS • Cell membrane pinches apart into two equal parts with one nucleus in each daughter cell • PLANT CELLS • Cell plate forms between two nuclei • Cell plate develops into a cell wall
Animations http://www.johnkyrk.com/mitosis.html http://www.hybridmedicalanimation.com/anim_mitosis.html
Activity • Each person will need one sheet of paper. • Name, block and date at the top right. • Title: Mitosis Quiz • I will show each slide in turn. • Number your answers according to the numbered picture/word. • Do not forget to label identifying marks on pictures.
CYTOKINESIS 1.
METAPHASE 4.
PROPHASE 7.
ANAPHASE 9.