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Sexual Reproduction. Meiosis – the formation of sex cells. Vocabulary. Somatic Cell Gamete Homologous Chromosomes Diploid Cells ( 2n ) Haploid Cells ( n ). Normal body cell Sex cell – sperm or egg Matching pairs of chromosomes Cells that have homologous chromosomes (somatic cells)
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Sexual Reproduction Meiosis – the formation of sex cells
Vocabulary • Somatic Cell • Gamete • Homologous Chromosomes • Diploid Cells ( 2n ) • Haploid Cells ( n ) • Normal body cell • Sex cell – sperm or egg • Matching pairs of chromosomes • Cells that have homologous chromosomes (somatic cells) • Cells that have only one chromosome from each pair (gametes)
Which cell is diploid and which is haploid? Haploid Cell Diploid Cell
Mitosis vs. Meiosis Mitosis Meiosis Sexual Reproduction Results in four genetically different daughter cells Creates haploid ( n ) cells Involves two cell divisions • Asexual Reproduction • Results in two genetically identical daughter cells • Creates diploid ( 2n ) cells • Involves one cell division
Prophase I • Homologous chromosomes form a tetrad • Segments of chromatids are exchanged
Metaphase I • Tetrads line up at the center of the cell
Anaphase I • Fibers pull tetrads apart • Haploid chromosomes move to opposite sides of cell
Telophase • Two haploid cells are formed
Prophase II • New fibers form and begin to connect to haploid chromosomes
Metaphase II • Chromosomes line up along the middle of the cell
Anaphase II • Chromatids of each chromosome separate and move towards opposite sides of the cells
Telophase II • Both cells divide to form four haploid cells containing half of the normal chromosome number. • Haploid cells turn into either sperm or egg cells depending on where they are formed.