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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