10.2 CellDivision

Prokaryotes: just separate into twoEukaryotes: Two stages

mitosis division of nucleuscytokinesis dividing cytoplasm in two

Chromosomes: Only visible during cell divisionAt other times chromatinAt cell division, chromosomes have been duplicated, and so are seen as two sister chromatids

Chromosomes• Only visible during cell division•At cell division, chromosomes have been duplicated and are seen as two sister chromatids•joined at centromere

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Chromosomes:DNA twisted together with proteinshistonesThen twisted again and

again into chromatids

Cell CycleInterphase: time between divisions

cell growthduplication of genetic

materialMitosis: nucleus and chromosomes divideCytokinesis: cytoplasm divides

Cell Cycle

Cell CycleInterphase: time between divisions

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Cell CycleProphase: Chromatin organizes into chromosomes.Nuclear membrane breaks up

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Cell CycleMetaphase: Chromosomes line up along cell equator

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Cell CycleAnaphase: Chromosomes separate toward opposite poles

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Cell CycleTelophase: Nuclear membrane reformes. Cytokinesis begins.

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Cell Division: Mitosis

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Cell Division: Mitosis

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10.3 Regulating the Cell Cycle

A. Controls on Cell DivisionCells in a petri dish

10.3 Regulating the Cell Cycle

A. Controls on Cell DivisionCells in a petri dish

10.3 Regulating the Cell Cycle

A. Controls on Cell DivisionCells in a petri dish

10.3 Regulating the Cell Cycle

A. Controls on Cell DivisionCells in a petri dish

10.3 Regulating the Cell Cycle

A. Controls on Cell DivisionCells in a petri dish

10.3 Regulating the Cell CycleB. Cell Cycle Regulators

CyclinsRegulate timing of cell cycle1. Internal Regulators•cell won’t enter mitosis until

chromosomes are replicated•cell won’t enter anaphase until

chromosomes are attached to the spindle

10.3 Regulating the Cell Cycle2. External Regulators

wound healingembryo development

10.3 Regulating the Cell CycleC. Uncontrolled Cell GrowthCancer cells to not respond to usual regulatory signals, resulting in tumors.

Gene p53“Cancer is a disease of the cell cycle”