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Transcript
Meiosis http://www.biology.arizona.edu/cell_bio/tutorials/ meiosis/main.html Interphase • Same as in mitosis • Growth and Replication • G1 – cell growth • S – replication of chromosoms • G2 – growth and preparation for cell division Chromosomes Karotype Prophase I • Chromosomes thicken and condense ( become visible) • Centrioles move to the poles • Nuclear envelop disappears • Homologous chromosomes come together during SYNAPSIS to form a TETRAD • Crossing-over occurs Metaphase I • Chromosomes move to the equator as a tetrad • Spindle fibers attach to chromosome Anaphase I • Spindle fibers shorten • Homologous chromosomes separate and move to the poles Telophase I / Cytokinesis • Cell membrane begins to pinch in • Nuclear membrane reappears • The cytoplasm divides • Formation of cell membrane • Results in two haploid daughter cells Meiosis II • Proceeds just as mitosis with the exception of chromosome replication. THEY DO NOT REPLICATE AGAIN!!! • • • • • Prophase II Metaphase II Anaphase II Telophase II Cytokinesis ??????????????????????