Somatic Cellular Reproduction:Somatic Cellular Reproduction:

The Cell Cycle and MitosisThe Cell Cycle and Mitosis1

Cells that make up the “body” of an organism Cells that make up the “body” of an organism 2

Why Should Cells Divide???Why Should Cells Divide???

In Unicellular Organisms: In Unicellular Organisms:

• ReproductionReproduction

In Multicellular Organisms: In Multicellular Organisms:

• Maintain a favorable surface area to Maintain a favorable surface area to volume ratiovolume ratio

• Maintain correct number of chromosomesMaintain correct number of chromosomes3

Structures that contain the genetic Structures that contain the genetic materialmaterial

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Chromosomes are composed of chromatin, a Chromosomes are composed of chromatin, a tangled mass of DNA and proteinstangled mass of DNA and proteins

The Full Number of The Full Number of Chromosomes Found in all Chromosomes Found in all Somatic Cells is the Somatic Cells is the Diploid Diploid NumberNumber (2N) (2N)

The Diploid Number The Diploid Number includes 2 of each includes 2 of each chromosome (a pair)chromosome (a pair)

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Each Chromosome contains two identical Each Chromosome contains two identical parts called “sister chromatids” attached at a parts called “sister chromatids” attached at a centromerecentromere

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The cycle of growth and division in all cellsThe cycle of growth and division in all cells

Consists of Interphase and MitosisConsists of Interphase and Mitosis

• Mitosis (M phase) is a period of cell divisionMitosis (M phase) is a period of cell division

• Interphase is a period of DNA replication and growth in Interphase is a period of DNA replication and growth in preparation for cell division preparation for cell division

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The Cell CycleThe Cell Cycle

GrowthGrowth

Protein SynthesisProtein Synthesis Cell DivisionCell Division

DNA copies DNA copies itselfitself

interphaseinterphase mitosismitosis

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Growth and DNA synthesis Growth and DNA synthesis and Replication (Gand Replication (G11, S, G, S, G22))

Longest period of Cell CycleLongest period of Cell Cycle

Chromatin in nucleus Chromatin in nucleus appears as mass of threadlike appears as mass of threadlike structuresstructures

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Stages of

Mitosis

Prophase - forward/beforeMetaphase - change (metamorphosis)Anaphase - backwardTelophase - endInterphase - between (intermission)

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•Chromatin Condensed Into Visible ChromosomesChromatin Condensed Into Visible Chromosomes

•Nucleolus Disappears and Nuclear Envelope FragmentsNucleolus Disappears and Nuclear Envelope Fragments

•Centrioles move to opposite sides of the cellCentrioles move to opposite sides of the cell

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•Chromosomes lined up on equatorial plateChromosomes lined up on equatorial plate

•Spindle fibers attach at centromeresSpindle fibers attach at centromeres

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•Centromeres divideCentromeres divide•Sister chromatids pulled towards the polesSister chromatids pulled towards the poles

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•Spindles disappear and nuclear envelope returnsSpindles disappear and nuclear envelope returns

•Nucleolus returnsNucleolus returns

•Chromosomes unwind into chromatinChromosomes unwind into chromatin

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Animal CellAnimal Cell Plant CellPlant Cell

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Identify the Stages of MitosisIdentify the Stages of Mitosis

11 22 33

44 55

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