Mitosis and the Cell Cycle Cell Cycle A

Cell Cycle: A repetitious event ¨ Three Main areas: – Interphase, Mitosis, & Cytokinesis

Cell Cycle: Big Picture Mitosis Growth 2 Growth 1 Synthesis

Mitosis in depth ¨ Shortest phase of the cell cycle ¨ Many things going

Prophase ¨ Longest phase of mitosis ¨ Chromatin coils up into visible chromosomes (sister

Metaphase ¨ Short second phase of mitosis ¨ Spindle fibers attach to centromeres and

Metaphase Sister Chromatids are lined up in the middle of the cell

Anaphase ¨ Shortening of the spindle fibers pulls chromatid sisters apart. ¨ Chromatids separate

Telophase ¨ Final phase of mitosis ¨ Chromatids are at opposite poles(ends) of the

Cytokinesis ¨ Cell’s cytoplasm divides in half – Resulting in two new daughter cells

Summary ¨ Cell Cycle: Three main phases – Interphase – Mitosis – Cytokinesis ¨

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Mitosis and the Cell Cycle

Cell Cycle: A repetitious event ¨ Three Main areas: – Interphase, Mitosis, & Cytokinesis ¨ Interphase – Growth 1 (Gap 1): Cell increases in size, prepares for DNA copying – Synthesis (S-phase): DNA gets copied (2 copies of DNA) – Growth 2 (Gap 2): Cell grows more, make more proteins, centrioles replicate ¨ Mitosis: Nucleus divides ¨ I. P. M. A. T ¨ Cytokinesis: cell membrane pinches into two or cell plate grows

Cell Cycle: Big Picture Mitosis Growth 2 Growth 1 Synthesis

Big Picture for Mitosis

Mitosis in depth ¨ Shortest phase of the cell cycle ¨ Many things going on in the cell ¨ One cell becomes two daughter cells – Virchow “Every cell comes from a preexisting cell” ¨ Four main phases: – Prophase, Metaphase, Anaphase, Telophase

Prophase ¨ Longest phase of mitosis ¨ Chromatin coils up into visible chromosomes (sister chromatids) – Connected by a centromere ¨ Nuclear envelope and nucleolus disappear ¨ Centrioles migrate to opposite ends of the cell – Spindle fibers form between centrioles

Prophase

Metaphase ¨ Short second phase of mitosis ¨ Spindle fibers attach to centromeres and move chromatid sisters to the center of the cell

Metaphase Centromeres

Metaphase

Metaphase Sister Chromatids are lined up in the middle of the cell

Anaphase ¨ Shortening of the spindle fibers pulls chromatid sisters apart. ¨ Chromatids separate and go to opposite ends of the cell

Anaphase

Telophase ¨ Final phase of mitosis ¨ Chromatids are at opposite poles(ends) of the cell ¨ Spindle fibers break down, nucleus amd nucleolus start to reappear ¨ Double membrane begins to form between nuclei

Telophase

Cytokinesis ¨ Cell’s cytoplasm divides in half – Resulting in two new daughter cells ¨ Daughter Cells go into Interphase, the cell cycle begins again

Telophase

Cytokinesis

Daughter cells go into Interphase

Summary ¨ Cell Cycle: Three main phases – Interphase – Mitosis – Cytokinesis ¨ Interphase: Longest part of cell cycle ¨ Mitosis: Division of the nucleus into two nuclei – 4 stages: Prophase, Metaphase, Anaphase, Telophas ¨ Cytokinesis: the division of the cell membrane into two daughter cells