QODQODHow many chromosomes do How many chromosomes do you have? Identify them. you have? Identify them.

How many from your How many from your father? Mother?father? Mother?

Chapter 8: Cell Chapter 8: Cell ReproductionReproduction

Section 8-1: ChromosomesSection 8-1: Chromosomes

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ChromosomeStructure

Chromosome StructureChromosome Structure

Chromosomes = DNA + ProteinsChromosomes = DNA + Proteins Levels of organization:Levels of organization:

– DNADNA– Nucleosome = DNA + HistonesNucleosome = DNA + Histones– CoilsCoils– SupercoilsSupercoils– ChromosomeChromosome

Chapter 8Chromosome StructureChromosome Structure

Section 1 Chromosomes

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Chromosome

ChromosomesChromosomes

Before Cell DivisionBefore Cell Division– ChromatinChromatin– Thinned outThinned out

During Cell DivisionDuring Cell Division– ThickenedThickened– ChromosomesChromosomes

Chromatids (2)Chromatids (2)CentromereCentromere

Chromosome Types and NumbersChromosome Types and Numbers

Types:Types:– Sex chromosomesSex chromosomes– AutosomesAutosomes– Homologous chromosomesHomologous chromosomes– KaryotypeKaryotype

Numbers:Numbers:– Diploid (2n)Diploid (2n)– Haploid (n)Haploid (n)

KaryotypeKaryotype

KaryotypeKaryotype

QODQODHow many chromosomes How many chromosomes

does a skin cells have after does a skin cells have after it divides by mitosis? What it divides by mitosis? What

happens to ensure this happens to ensure this number is achieved? number is achieved?

When?When?

Chapter 8: Cell Chapter 8: Cell ReproductionReproduction

Section 8-2: Cell DivisionSection 8-2: Cell Division

Cell DivisionCell Division

In ProkaryotesIn Prokaryotes– Binary fissionBinary fission

In EukaryotesIn Eukaryotes– MitosisMitosis– MeoisisMeoisis

Section 2 Cell DivisionChapter 8

Cell Division in ProkaryotesCell Division in Prokaryotes

QODQODDefine mitosis. What is the Define mitosis. What is the

end result of mitosis?end result of mitosis?

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Stages ofCell Cycle

III. The Cell CycleIII. The Cell Cycle

InterphaseInterphase– G1G1– SS– G2G2

M PhaseM Phase– MitosisMitosis– CytokinesisCytokinesis

The M phaseThe M phase

Mitosis – Division of the nucleusMitosis – Division of the nucleus– ProphaseProphase– MetaphaseMetaphase– AnaphaseAnaphase– TelophaseTelophase

Cytokinesis – Division of the Cytokinesis – Division of the cytoplasmcytoplasm

MitosisMitosis

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Animal cell undergoing mitosis

ProphaseProphase

Nucleus disappearsNucleus disappears Centrosomes/Centrioles moveCentrosomes/Centrioles move Spindle fibers form – mitotic spindleSpindle fibers form – mitotic spindle

– Kinetochore fibers/ KinetochoreKinetochore fibers/ Kinetochore– Polar fibersPolar fibers

Mitosis continuesMitosis continues

MetaphaseMetaphase– Metaphase plateMetaphase plate

AnaphaseAnaphase– Role of kinetochoreRole of kinetochore

TelophaseTelophase– Reversal of prophaseReversal of prophase– Results:Results:

QODQODHow does the cell control How does the cell control

the cell cycle? What the cell cycle? What happens when control is happens when control is

lost?lost?

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Animal cell undergoing mitosis

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Plant Cell Undergoing Mitosis

CytokinesisCytokinesis

Division of the cytoplasmDivision of the cytoplasm Separates two nuclei into two distinct Separates two nuclei into two distinct

daughter cellsdaughter cells Animal cells – cleavageAnimal cells – cleavage Plant cells – form cell platePlant cells – form cell plate

Control of Cell DivisionControl of Cell Division

Checkpoints:Checkpoints:– G1G1– G2G2– MitosisMitosis

Loss of controlLoss of control– CancerCancer

QODQODCompare and contrast Compare and contrast

mitosis to meiosismitosis to meiosis

Chapter 8: Cell Chapter 8: Cell ReproductionReproduction

Section 8-3: MeiosisSection 8-3: Meiosis

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HomologousChromosome

MeiosisMeiosis

““Reduction” divisionReduction” division Produces gametesProduces gametes 2 divisions2 divisions Diploid Diploid haploid haploid Fertilaztion – n + n = 2nFertilaztion – n + n = 2n

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MeiosisDiagram

Meiosis IMeiosis I

Prophase IProphase I– Much of it same as prophase in mitosisMuch of it same as prophase in mitosis

Nucleus/nucleolus disappearsNucleus/nucleolus disappearsChromosomes coilChromosomes coilCentrioles and spindle fibersCentrioles and spindle fibers

– Homologous chromosomes pair upHomologous chromosomes pair upSynapsisSynapsisForms a tetradForms a tetradCrossing-over Crossing-over genetic recombination genetic recombination

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Crossing Over Diagram

QODQODWhat is independent What is independent

assortment?assortment?

Meiosis IMeiosis I

Metaphase IMetaphase I– Tetrads line upTetrads line up

Anaphase IAnaphase I– Independent assortment Independent assortment genetic genetic

variationvariation Telophase ITelophase I

– Cytokinesis beginsCytokinesis begins– Forms 2 haploid cellsForms 2 haploid cells

LE 13-8ab

Sisterchromatids

Chiasmata

Spindle

Centromere(with kinetochore)

Metaphaseplate

Homologouschromosomesseparate

Sister chromatidsremain attached

Microtubuleattached tokinetochore

Tetrad

MEIOSIS I: Separates homologous chromosomes

PROPHASE I METAPHASE I ANAPHASE I

Homologous chromosomes (red and blue) pair andexchange segments; 2n = 6in this example

Pairs of homologouschromosomes split up

Tetrads line up

Meiosis IIMeiosis II

No copying of DNANo copying of DNA Follows process of mitosisFollows process of mitosis Prophase IIProphase II Metaphase IIMetaphase II Anaphase IIAnaphase II Telophase IITelophase II CytokinesisCytokinesis

LE 13-8b

Cleavagefurrow

MEIOSIS II: Separates sister chromatids

PROPHASE II METAPHASE II ANAPHASE IITELOPHASE I AND

CYTOKINESISTELOPHASE II AND

CYTOKINESIS

Sister chromatidsseparate

Haploid daughter cellsforming

Two haploid cellsform; chromosomesare still double

During another round of cell division, the sister chromatids finally separate;four haploid daughter cells result, containing single chromosomes

ResultsResults

GametesGametes– 4 haploid cells4 haploid cells– Genetically differentGenetically different

Males:Males:– SpermatogensisSpermatogensis

Females:Females:– OogenesisOogenesis– 1 egg cell, 3 polar bodies1 egg cell, 3 polar bodies

Chapter 8

Meiosis in Male and Female Meiosis in Male and Female AnimalsAnimals

Section 3 Meiosis