Cell DivisionCell Division

ChromosomesChromosomes

Are made of DNAAre made of DNA Each chromosome consists of sister Each chromosome consists of sister

chromatids attached at a centromerechromatids attached at a centromere

Cell CycleCell Cycle

During the cell cycle, a cell grows, During the cell cycle, a cell grows, prepares for division, and divides to prepares for division, and divides to form 2 daughter cells, each with form 2 daughter cells, each with each of which then begins the cycle each of which then begins the cycle again.again.

Interphase – time for growth and Interphase – time for growth and regular cell activity.regular cell activity.

Most of a cells life is spent in Most of a cells life is spent in Interphase.Interphase.

InterphaseInterphase

Introduction to Cell DivisionIntroduction to Cell Division

MitosisMitosis

The division of somatic or regular The division of somatic or regular cells.cells.

Its divided into 4 phases.Its divided into 4 phases. Remember Interphase is NOT part of Remember Interphase is NOT part of

Mitosis.Mitosis.

Introduction to MitosisIntroduction to Mitosis

ProphaseProphase

First stage of MitosisFirst stage of Mitosis Chromatin condenses into Chromatin condenses into

chromosomeschromosomes Centrioles separate and a spindle Centrioles separate and a spindle

fiber begins to form.fiber begins to form. Nuclear membrane breaks downNuclear membrane breaks down

ProphaseProphase

MetaphaseMetaphase

Second Phase of MitosisSecond Phase of Mitosis Chromosomes line up in the middle Chromosomes line up in the middle

of the cell.of the cell. Each chromosome is connected to a Each chromosome is connected to a

spindle fiber.spindle fiber.

MetaphaseMetaphase

AnaphaseAnaphase

Third Phase of MitosisThird Phase of Mitosis The sister chromatids separate into The sister chromatids separate into

individual chromosomes and move individual chromosomes and move apart to opposite ends of the cell.apart to opposite ends of the cell.

AnaphaseAnaphase

TelophaseTelophase

Fourth and Final Stage of MitosisFourth and Final Stage of Mitosis Chromosomes gather at opposite Chromosomes gather at opposite

ends of the cell and lose their distinct ends of the cell and lose their distinct shapesshapes

Two new nuclear membranes have Two new nuclear membranes have formed.formed.

TelophaseTelophase

CytokinesisCytokinesis

The cytoplasm pinches in half.The cytoplasm pinches in half. Each daughter cell has an identical Each daughter cell has an identical

set of duplicate chromosomesset of duplicate chromosomes

Regulating the CycleRegulating the Cycle

A protein call cyclin helps regulate A protein call cyclin helps regulate the cell cycle in eukaryotic cells.the cell cycle in eukaryotic cells.

They respond to internal and They respond to internal and external events. These proteins are external events. These proteins are regulators.regulators.

When Things Go WrongWhen Things Go Wrong

Cancer cells do not respond to the Cancer cells do not respond to the signals that regulate the growth of signals that regulate the growth of most cells.most cells.

As a result, they form masses of cells As a result, they form masses of cells called tumors that can damage called tumors that can damage surrounding tissues.surrounding tissues.

CancerCancer