CH 13 PPT Meiosis - Sargent Central Public School

Interphase Homologous pair of chromosomes in diploid parent cell Chromosomes replicate Homologous pair of replicated chromosomes Sister chromatids Diploid cell with replicated chromosomes Meiosis I 1 Homologous chromosomes separate

Haploid cells with replicated chromosomes Meiosis II 2 Sister chromatids separate Haploid cells with unreplicated chromosomes Prophase I Metaphase I Centrosome (with centriole pair) Sister chromatids Centromere (with kinetochore) Chiasmata

Spindle Metaphase plate Sister chromatids remain attached Homologous chromosomes separate Homologous chromosomes Fragments of nuclear envelope Microtubule attached to kinetochore

Telophase I and Cytokinesis Anaphase I Cleavage furrow Prophase I Metaphase I Centrosome (with centriole pair) Sister chromatids Chiasmata Spindle Centromere

(with kinetochore) Metaphase plate Homologous chromosomes Fragments of nuclear envelope Microtubule attached to kinetochore Telophase I and Cytokinesis Anaphase I Sister chromatids remain attached

Homologous chromosomes separate Cleavage furrow Prophase II Metaphase II Anaphase II Telophase II and Cytokinesis Sister chromatids separate Haploid daughter cells

forming Prophase II Metaphase II Anaphase II Telephase II and Cytokinesis Sister chromatids separate Haploid daughter cells forming MITOSIS MEIOSIS Parent cell

Chromosome replication Prophase Chiasma Chromosome replication Prophase I Homologous chromosome pair 2n = 6 Replicated chromosome MEIOSIS I

Metaphase Metaphase I Anaphase Telophase Anaphase I Telophase I Haploid n=3 Daughter cells of meiosis I 2n Daughter cells of mitosis 2n

MEIOSIS II n n n n Daughter cells of meiosis II SUMMARY Property Mitosis Meiosis DNA replication Occurs during interphase before mitosis begins Occurs during interphase before meiosis I begins

Number of divisions One, including prophase, metaphase, anaphase, and telophase Two, each including prophase, metaphase, anaphase, and telophase Synapsis of homologous chromosomes Does not occur Occurs during prophase I along with crossing over between nonsister chromatids; resulting chiasmata hold pairs together due to sister chromatid cohesion Number of

daughter cells and genetic composition Two, each diploid (2n) and genetically identical to the parent cell Four, each haploid (n), containing half as many chromosomes as the parent cell; genetically different from the parent cell and from each other Role in the animal body Enables multicellular adult to arise from zygote; produces cells for growth, repair, and, in some species, asexual reproduction Produces gametes; reduces number of chromosomes by half and introduces genetic variability among the gametes

Possibility 2 Possibility 1 Two equally probable arrangements of chromosomes at metaphase I Metaphase II Daughter cells Combination 1 Combination 2 Combination 3 Combination 4 Prophase I of meiosis Pair of homologs

Nonsister chromatids held together during synapsis Chiasma Centromere TEM Anaphase I Anaphase II Daughter cells Recombinant chromosomes 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 Mei osis 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