Warm up 12/10 What are the 4 ½ steps of Mitosis in order. –Write one sentence each describing how you can identify the steps.

Meiosis pp

Double mitosis Results in haploid cells (n)  gametes 2n  4n  (2) 2n  (4) n two stages of meiosis (I and II) CLIP

Meiosis I 1. Similar to the phases of mitosis 2. 2n  4n  (2) 2n 3. separating into homologous chromosomes

Two important things occur in meiosis I that do not occur in mitosis crossing over and independent assortment

Synapsis: during prophase I chromosomes line up with homologues via corresponding genes to make a tetrad Crossing-over: random exchange of genetic material during synapsis - homologous pairs overlap and twist on each other (not always the exact same spot!!) Independent assortment: random separation of the homologous chromosomes occur during anaphase I

Meiosis II: begins right after meiosis I 1. (2) 2n  (4) n ; 4 haploid cells 2. separating into single chromatids CLIP

Meiosis is the formation of Gametes spermatogenesis (testes): males produce sperm cells oogenesis (ovaries): females make eggs and produce one egg and 3 polar bodies (useless) at the end of one cycle of meiosis- occurs only at ovulation