Terms Haploid: (1n) one set of chromosomes Diploid: (2n) two sets of chromosomes Gametes: sex cells Female = egg cells Male = sperm cells Somatic Cells: (autosomes) body cells (ex: skin, stomach, brain, liver, blood cells)

Crossing Over During prophase I, the homologous chromosomes form tetrads, which may exchange genetic information.

Independent Assortment of chromosomes The chromosomes line up during metaphase I at random which leads to genetic variability (differences). Inherited from father (blue) Inherited from mother (red)

Meiosis: Cell division process that reduces the number of chromosomes present by ½ (creates egg and sperm cells)

Meiosis Interphase Meiosis is proceded by interphase. The chromosomes have not yet condensed. http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

Meiosis Interphase chromosomes replicated chromatin condenses. http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

Meiosis Prophase I Chromosomes completely condensed. In meiosis (unlike mitosis), homologous chromosomes pair with one another forming a tetrad Crossing over occurs http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

Meiosis Metaphase I Homologous chromosomes attach to spindle fibers - line up in the middle (equator). Independent Assortment occurs http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

Meiosis Anaphase I Homologous chromosome pair move to opposite ends of the cell. (2n  1n) http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

Meiosis Telophase I & Cytokinesis Cell begins to divide into two daughter cells. Each daughter cell can get any combination of maternal and paternal chromosomes. http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

Meiosis Prophase II Cell has divided into two daughter cells. Centrioles migrate, spindles form, chromosomes pairs begin to migrate. http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

Meiosis Metaphase II As in Meiosis I, the chromosomes line up on the spindle fibers across the middle (equator). http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

Meiosis Anaphase II As in Meiosis I, the sister chromatids move to opposite ends of each cell. http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html

Telophase II & Cytokinesis Four haploid cells. Each gamete (sex cell) carries half the number of chromosomes of somatic (body) cells. http://morgan.rutgers.edu/MorganWebFrames/Level1/Page7/meiosis1.html