1	Meiosis and Sexual Reproduction
2	Meiosis 1. Starts with homologous chromosomes 2. Involves two divisions of the nucleus 3. Divisions called: Meiosis I and meiosis II
3	"4." 4. Each meiosis, I and II, are divided into the four phases of prophase, metaphase, anaphase and telophase 5. Result is that four haploid cells are formed.
4	Meiosis Stages in meiosis: Meiosis I – prophase I, metaphase I, anaphase I, telophase I Meiosis II – prophase II, metaphase II, anaphase II, telophase II
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6	Question? Why is it that you look a little like your mom and a little like your dad?
7	Crossing-over
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9	Independent Assortment The random distribution of chromosomes during meiosis results in millions of different gametes. This independent assortment produces millions upon millions of possible combinations of gametes for fertilization between sperm and egg.
10	Independent Assortment 1. Twenty-three pairs of chromosomes separate independently. 2. Thus, out of these 23 pairs of chromosomes over 8,000,000 different gametes, with different genetic information, can be formed.
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12	Crossing-over and random fertilization results in…
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14	Meiosis and gamete formation
15	Gamete Formation 1. Formation of the egg is called oogenesis à the female gamete, or egg, is called an ovum. 2. Formation of the sperm is called spermatogenesis. à the male gamete is called sperm.
16	Gamete Formation Spermatogenesis results in the production of four sperm while, oogenesis results in only one good ovum or egg with the other three being called polar bodies.
17	Oogenesis or ovum (egg) formation
18	This is why there are sooooo many more sperm to fertilize one egg.
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20	Mitosis versus Meiosis 1. Mitosis produces diploid cells 2. Meiosis produces haploid cells 3. Mitosis produces two cells with the same genetic (DNA) material 4. Meiosis produces four cells with different genetic material.
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22	The End