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Meiosis I: Reduction Division

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Presentation on theme: "Meiosis I: Reduction Division"— Presentation transcript:

1 Meiosis I: Reduction Division
Nucleus Spindle fibers Nuclear envelope Early Prophase I (Chromosome number doubled) Late Prophase I Metaphase I Anaphase I Telophase I (diploid) 1 1

2 Prophase I Late prophase Early prophase Chromosomes condense.
Spindle forms. Nuclear envelope fragments. Early prophase Homologs pair. Crossing over occurs. 2 2

3 Tetrads Form in Prophase I
Homologous chromosomes (each with sister chromatids)   Join to form a TETRAD Called Synapsis 3 3

4 Crossing-Over Homologous chromosomes in a tetrad cross over each other
Pieces of chromosomes or genes are exchanged Produces Genetic recombination in the offspring 4 4

5 Homologous Chromosomes During Crossing-Over
5 5

6 Crossing-Over Crossing-over multiplies the already huge number of different gamete types produced by independent assortment 6 6

7 Homologous pairs of chromosomes align along the equator of the cell
Metaphase I Homologous pairs of chromosomes align along the equator of the cell 7 7

8 Anaphase I Homologs separate and move to opposite poles.
Sister chromatids remain attached at their centromeres. 8 8

9 Telophase I Nuclear envelopes reassemble. Spindle disappears.
Cytokinesis divides cell into two. 9 9


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