Eukaryotic Cell Division Stage 1: MitosisStage 1: Mitosis Stage 2: CytokinesisStage 2: Cytokinesis

Eukaryotic Cell Eukaryotic Cell DivisionDivision

•Stage 1: MitosisStage 1: Mitosis•Stage 2: CytokinesisStage 2: Cytokinesis

Interphase-(the Interphase-(the long period)long period)

• G1 Phase: Cell grows, makes G1 Phase: Cell grows, makes new proteins and organellesnew proteins and organelles

• G0 Phase: Cells “hang out” and G0 Phase: Cells “hang out” and perform usual functionsperform usual functions

• S Phase: DNA is replicatedS Phase: DNA is replicated

• G2 Phase: OrganellesG2 Phase: Organelles required required for division are synthesizedfor division are synthesized

•The shortest part of the The shortest part of the cell cyclecell cycle

•Lasts from a few minutes Lasts from a few minutes to several daysto several days

•Consists of 4 Phases:Consists of 4 Phases:

--ProphaseProphase

--MetaphaseMetaphase

--AnaphaseAnaphase

--TelophaseTelophase

• Nuclear envelope Nuclear envelope dissolvesdissolves

• Nucleolus disappearsNucleolus disappears• Chromosomes become Chromosomes become

visiblevisible• Centrioles move to polesCentrioles move to poles• Spindle fibers formSpindle fibers form

• Chromosomes line up at the Chromosomes line up at the equator (center)equator (center)

• Spindles connect to the Spindles connect to the centromere of each chromosomecentromere of each chromosome

• Centrioles split chromosomes Centrioles split chromosomes into sister chromatids into sister chromatids

• Phase ends once Phase ends once chromatids chromatids reach the polesreach the poles

• Chromosomes uncoilChromosomes uncoil• A nuclear envelope A nuclear envelope

surrounds DNA surrounds DNA • Nucleolus re-formsNucleolus re-forms• Spindle fibers break downSpindle fibers break down• Cell division is not complete!Cell division is not complete!

•Divides cytoplasmDivides cytoplasm

In plants, a In plants, a cell plate cell plate

forms forms between the between the 2 new cells2 new cells

Forms new Forms new cell wall!cell wall!

MeiosisMeiosis

DuringDuring sexual sexual reproductionreproduction,, gametesgametes

(sperm or eggs) (sperm or eggs) are are produced by each parentproduced by each parent

Gametes contain Gametes contain halfhalf the number of the number of

chromosomes found in chromosomes found in most cellsmost cells

Dad’s Dad’s

chromosomeschromosomes Mom’s Mom’s

chromosomeschromosomes

Dad’s Dad’s

gametesgametes Mom’s Mom’s

gametesgametes When gametes unite, the When gametes unite, the

zygotezygote then has the then has the normalnormal number of number of

chromosomeschromosomeszygotezygote

Diploid vs. Diploid vs. HaploidHaploid

DIPLOID: DIPLOID: Contains Contains

BOTH sets of BOTH sets of chromosomes chromosomes (1 from each (1 from each

parent)parent)HAPLOID: Contains 1 HAPLOID: Contains 1 set of chromosomes set of chromosomes to combine during to combine during

sexual reproduction sexual reproduction with another to form with another to form

a DIPLOID cell. a DIPLOID cell.