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

CYTOKINESIS the division of the cytoplasm to make two complete daughter cells 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

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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.

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METAPHASE 4.

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PROPHASE 7.

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ANAPHASE 9.

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