Cell Cycle Notes Mitosis Definition Mitosis is the

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Cell Cycle Notes

Cell Cycle Notes

Mitosis Definition Mitosis is the process in which a eukaryotic cell separates the chromosomes

Mitosis Definition Mitosis is the process in which a eukaryotic cell separates the chromosomes in its cell nucleus, into two identical sets in two daughter nuclei.

Why must cells divide? Growth – bigger organisms need more cells (You, yes you,

Why must cells divide? Growth – bigger organisms need more cells (You, yes you, started as ONE cell!) Repair – regeneration of skin, blood, bone, etc. Reproduction – sexual vs asexual

Mitosis • Cell Division occurs in a series of stages or phases. – Interphase

Mitosis • Cell Division occurs in a series of stages or phases. – Interphase – Prophase – Metaphase – Anaphase – Telophase – Cytokinesis

The Cell Cycle Interphase – cell spends 90% of its time here G 1

The Cell Cycle Interphase – cell spends 90% of its time here G 1 – growth phase one S – synthesis phase G 2 – growth phase two Mitosis Prophase Metaphase Anaphase Telophase Cytokinesis Division of cell into 2 new cells with identical DNA

Mitosis

Mitosis

Interphase 1. Growth 1 (G 1) 1. 2. 3. Growth of cell organelles, chromosomes

Interphase 1. Growth 1 (G 1) 1. 2. 3. Growth of cell organelles, chromosomes are stretched out and actively giving directions for proteins Synthesis (S) 1. Chromosomes are replicated and condensed (# doubles) – each chromosome appears as a threadlike coil (chromatin) 2. Copy is called sister chromosome 3. Sister chromosomes change to sister chormatids at the end of the phase. Growth 2 (G 2) 1. Final growth phase, cell makes sure there are enough organelles for each new cell to split during cytokinesis

A bit about chromosome terminology. . . Sister Chromatids

A bit about chromosome terminology. . . Sister Chromatids

Prophase (This is the OFFICIAL start of “MITOSIS”) Chromosomes condense very tightly and are

Prophase (This is the OFFICIAL start of “MITOSIS”) Chromosomes condense very tightly and are now visible. Centrioles (or poles) appear and begin to move to opposite ends of the cell Spindle fibers form between the poles Nuclear envelope breaks down

Metaphase Chromatids (pairs of chromosomes) line up in middle of cell across “equator” Centromere

Metaphase Chromatids (pairs of chromosomes) line up in middle of cell across “equator” Centromere (holds sisters together) attaches to spindle fiber

Anaphase Centromere divides (sister chromatids separate) Spindle fibers pull chromatids apart Chromosomes move to

Anaphase Centromere divides (sister chromatids separate) Spindle fibers pull chromatids apart Chromosomes move to opposite sides of cell

Telophase Kind of the reverse of Prophase Two new nuclei form Nuclear envelope reforms

Telophase Kind of the reverse of Prophase Two new nuclei form Nuclear envelope reforms Chromosomes uncoil Chromosomes appears as chromatin (threads rather than rods) Spindle fibers break down Mitosis Ends

Cytokinesis Separation of the cytoplasm Cell membrane moves inward to create two daughter cells

Cytokinesis Separation of the cytoplasm Cell membrane moves inward to create two daughter cells Each has its own nucleus and identical chromosomes A little bit different in plants than animals

Result of Mitosis Two new cells with identical DNA (cell directions).

Result of Mitosis Two new cells with identical DNA (cell directions).

The Cell Cycle Review Interphase – cell spends 90% of its time here G

The Cell Cycle Review Interphase – cell spends 90% of its time here G 1 – growth phase one S – synthesis phase G 2 – growth phase two Mitosis Prophase Metaphase Anaphase Telophase Cytokinesis Division of cell into 2 new cells with identical DNA