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Chapter 11-4 Cell Division A thread-like structure containing genetic information. b. Tightly coiled DNA strands c. Homologous • Pairs of chromosomes that contain information for the same biological features. For example eye color (One gene from each parent). d. Tetrad • The structure made when the homologous chromosomes join. a. Cell division resulting in the number of chromosomes in a cell being divided in half, through the separation of homologous chromosomes. Diploid cells divide to produce haploid cells. a. b. • • c. Haploid – Cells that contain “half” the genetic information. One set of chromosomes. (n) Diploid – Cells that contain both sets of homologous chromosomes. (2n) Only occurs in reproductive cells. Cell division process similar to mitosis. d. • Occurs during the “M Phase” of the cell cycle. • Similar phases: Prophase Metaphase Anaphase Telophase Cytokinesis • • • • • Unlike mitosis, MEIOSIS involves 2 divisions: Meiosis I and Meiosis II. a. • Produces 4 cells instead of 2. • Cells produced contain half the genetic information as the parent cell. b. Crossing Over: During prophase 1 the homologous chromosomes pair up and form tetrads, they also exchange genetic information. Gametes: Sex cells that contain half the genetic information (haploid) produced during meiosis. a. • • b. c. In males = sperm cells In females = egg cells (ova) Spermatogenesis: The process of making sperm cells. Occurs in the male reproductive organs, testes. Oogenesis: The process of making egg cells (ova). Occurs in the female reproductive organs, ovaries. d. Fertilization: The process of male and female haploid gametes (n) fusing to form a diploid zygote (2n).