Interphase

Homologous pair of chromosomesin diploid parent cell

Chromosomesreplicate

Homologous pair of replicated chromosomes

Sisterchromatids Diploid cell with

replicated chromosomes

Meiosis I

Homologouschromosomesseparate

1

Haploid cells withreplicated chromosomes

Meiosis II

2 Sister chromatidsseparate

Haploid cells with unreplicated chromosomes

Metaphase IProphase I Anaphase I Telophase I andCytokinesis

Centrosome(with centriole pair)

Sisterchromatids Chiasmata

Spindle

Homologouschromosomes

Fragmentsof nuclearenvelope

Centromere(with kinetochore)

Metaphaseplate

Microtubuleattached tokinetochore

Sister chromatidsremain attached

Homologouschromosomesseparate

Cleavagefurrow

Prophase I Metaphase I

Centrosome(with centriole pair)

Sisterchromatids Chiasmata

Spindle

Centromere(with kinetochore)

Metaphaseplate

Homologouschromosomes

Fragmentsof nuclearenvelope

Microtubuleattached tokinetochore

Anaphase ITelophase I and

Cytokinesis

Sister chromatidsremain attached

Homologouschromosomesseparate

Cleavagefurrow

Prophase II Metaphase II Anaphase II Telophase II andCytokinesis

Sister chromatidsseparate Haploid daughter cells

forming

Prophase II Metaphase II

Anaphase IITelephase II and

Cytokinesis

Sister chromatidsseparate Haploid daughter cells

forming

MITOSIS MEIOSIS

MEIOSIS I

Prophase I

Chiasma

Chromosomereplication

Homologouschromosomepair

Chromosomereplication

2n = 6

Parent cell

Prophase

Replicated chromosome

Metaphase Metaphase I

Anaphase ITelophase I

Haploid n = 3

Daughter cells ofmeiosis I

MEIOSIS II

Daughter cells of meiosis II

nnnn

2n2n

Daughter cellsof mitosis

AnaphaseTelophase

SUMMARY

MeiosisMitosisProperty

DNAreplication

Number ofdivisions

Occurs during interphase beforemitosis begins

One, including prophase, metaphase,anaphase, and telophase

Synapsis ofhomologouschromosomes

Does not occur

Number ofdaughter cellsand geneticcomposition

Two, each diploid (2n) and geneticallyidentical to the parent cell

Role in theanimal body

Enables multicellular adult to arise fromzygote; produces cells for growth, repair,and, in some species, asexual reproduction

Occurs during interphase before meiosis I begins

Two, each including prophase, metaphase, anaphase, andtelophase

Occurs during prophase I along with crossing overbetween nonsister chromatids; resulting chiasmatahold pairs together due to sister chromatid cohesion

Four, each haploid (n), containing half as many chromosomesas the parent cell; genetically different from the parentcell and from each other

Produces gametes; reduces number of chromosomes by halfand introduces genetic variability among the gametes

Possibility 1 Possibility 2

Two equally probablearrangements ofchromosomes at

metaphase I

Metaphase II

Daughtercells

Combination 1 Combination 2 Combination 3 Combination 4

Prophase Iof meiosis

Pair ofhomologs

Nonsisterchromatidsheld togetherduring synapsis

Chiasma

Centromere

Anaphase I

Anaphase II

Daughtercells

Recombinant chromosomes

TEM

Animations and Videos

• Meiosis Tutorial

• Meiosis - 1

• Meiosis - 2

• Stages of Meiosis

• Anaphase Separase

• Spermatogenesis

• Production of Male and Female Gametes

• Polar Body Formation

Animations and Videos

• Random Orientation of Chromosomes During Meiosis

• Independent Assortment

• Independent Assortment and Gamete Diversity

• Alleles That Do Not Assort Independently

• Comparison of Mitosis and Meiosis

• Bozeman - Diploid vs. Haploid Cells

• Activity- Mitosis and Meiosis

• Bozeman - Mitosis and Meiosis Simulation

Animations and Videos

• Meiosis - Nondisjunction – 1

• Meiosis - Nondisjunction – 2

• Crossing Over

• Changes in Chromosome Structure

• The Consequence of Inversion

• Bozeman - Cell Cycle (Mitosis and Meiosis)

• X Inactivation

• Bozeman - X Inactivation

Animations and Videos

• Density-Dependent Inhibition

• Cytotoxic T Lymphocytes Attack a Melanoma Cell

• Metastasis of a Cancer

• Amniocentesis Animation

• Chorionic Villus Sampling

• Karyotype Animation

• Human Melanoma Cells Dividing

• Chapter Quiz Questions – 1

• Chapter Quiz Questions – 2