qod how many chromosomes do you have? identify them. how many from your father? mother?
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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
Chromosome StructureChromosome Structure
Chromosomes = DNA + ProteinsChromosomes = DNA + Proteins Levels of organization:Levels of organization:
– DNADNA– Nucleosome = DNA + HistonesNucleosome = DNA + Histones– CoilsCoils– SupercoilsSupercoils– ChromosomeChromosome
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)
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
QODQODDefine mitosis. What is the Define mitosis. What is the
end result of mitosis?end result of mitosis?
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
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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?
To return to the chapter summary click escape or close this document.
Animal 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
MeiosisMeiosis
““Reduction” divisionReduction” division Produces gametesProduces gametes 2 divisions2 divisions Diploid Diploid haploid haploid Fertilaztion – n + n = 2nFertilaztion – n + n = 2n
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
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
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