Mitosis 5.2

I. Purpose To grow more cells  Example: Growing taller, growing roots To reproduce asexually  Example: Hydra buds to reproduce Repair damaged tissue  Example: A tear in skin –cells multiply to repair the tissue.

II. Overview Mitosis – the division of the eukaryotic cell’s nucleus Cells divide into 2 daughter cells Daughter cells are identical to parent cells  Each receives an exact copy of the chromosomes present in the parent cell Done in somatic cells - typical body cells

II. Overview Chromosome – coiled structures made of DNA and proteins; consists of two identical copies linked together (sister chromatids) Gene – organized chromosomal units that contain the instructions for a single protein

II. Overview There are 4 stages of mitosis: 1. Prophase 2. Metaphase 3. Anaphase 4. Telophase / Cytokinesis The rest of the cell’s life is spent in interphase. IPMAT!!

III. Stage #1- Prophase Chromatin in the nucleus coils and becomes distinct chromosomes. Chromosomes that were duplicated during the “S” phase join with their sister chromatid.  Join at the centromere

III. Stage #1 - Prophase A mitotic spindle grows out from centrioles in the cytoplasm. The nuclear envelope disappears. Spindle attaches to the centromere (kineticore) and pulls the chromosomes to the center.

III. Stage #1 - Prophase

IV. Stage #2 - Metaphase Centrioles are positioned at the poles. The chromosomes are lined up in the middle - the metaphase plate.  EQUATOR = MIDDLE Metaphase = Meet (in the Middle)

IV. Stage #2 - Metaphase The sister chromatids are lined up on either side of the plate The spindle is attached to each chromatid and prepares for separation.

V. Stage #3 - Anaphase The spindle fibers “reel” in the chromatids. The poles move farther apart.

V. Stage #3 - Anaphase The microtubules which make up the spindle get shorter, pulling the chromatids toward the poles. Anaphase = Away

VI. Stage #4 - Telophase A nucleus begins to reform in the new cell. Chromosomes lengthen into chromatin. Mitotic spindle disappears. Telophase = Terminal = End

VI. Stage #4 - Telophase A cleavage furrow appears, separating the two cells.  Checkpoint ! Cytokinesis - pinches the cell into two separate cells.

VII. Cytokinesis Division of cytoplasm Animal cells  cell membrane pinches together until the cell membrane separates forming 2 daughter cells Plant cells  relatively rigid; a cell plate formed in the middle of the dividing cell from membrane vesicles

VIII. Plant Cell Cytokinesis Plant cells form a plate between the two new cells that later becomes a cell wall.

Stages of Mitosis

Quick Review of Mitosis  Online Activity Online Activity  Exploring Life Exploring Life  Online Activity 2 Online Activity 2

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