Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Announcements • Test Corrections: 12/6 – 12/16 • Take Biospheres Home Question of the Day Question: What is mitosis and what does it create? Answer: … … … Biosphere Report: Part 2 Meiosis Notes & Vocabulary Sheet Before Mitosis: Phases of Mitosis: Interphase Prophase Metaphase Anaphase Telophase Interphase Prophase Metaphase Anaphase Telophase Unit 5 Vocabulary 19. mitosis- cell division resulting in 2 identical cells 18. meiosis- cell divisions resulting in 4 unique cells with half of the normal number of chromosomes Introduction • Meiosis is a type of cell division that makes cells with half the number of chromosomes • How 1N gametes (sex cells) are created Unit 5 Vocabulary 16. diploid (2n)- 2 sets of chromosomes 17. haploid (1n)- 1 set of chromosomes Introduction • Meiosis creates genetic diversity through the recombination of chromosomes • DNA is replicated during interphase beforehand • In meiosis, the cell will divide twice to make four 1N cells Meiosis I Prophase I • DNA coils into chromosomes • Spindle fibers appear • Homologous chromosomes pair together, forming a tetrad Unit 5 Vocabulary 24. homologs (homologous chromosomes)- a pair of corresponding chromosomes, 1 from each parent 25. tetrad- a pair of duplicated homologous chromosomes Meiosis I Prophase I • Portions of chromatids may break off and attach to adjacent chromosomes; this is called crossing-over • Crossing-over exchanges genetic material between maternal and paternal chromosomes 20. crossing over- sections of chromatids are broken off and exchanged Meiosis I Metaphase I • Spindle fibers attach • Tetrads line up in middle of cell Meiosis I Anaphase I • Homologous chromosomes are pulled apart to opposite ends of the cell • Which homologous chromosome goes to which end is random Meiosis I Telophase I • Cytokinesis occurs, forming two 1N cells Meiosis II Prophase II • Spindle fibers appear Meiosis II Metaphase II • Chromosomes move toward middle of the cell Meiosis II Anaphase II • Chromatids separate, pulled to opposite ends of each cell Meiosis II Telophase II • Cytokinesis occurs again • Four 1N cells are formed Formation of Gametes • Sperm and eggs are produced through meiosis – makes 4 sperm in testes – makes 1 ovum (egg) and 3 polar bodies in ovaries Unit 5 Vocabulary 9. ovum (ova)- a female sex cell or egg 10. sperm- a male sex cell 8. gamete- sex cells (ex: sperm or ovum) 7. somatic/body cell- a cell in an organism not used in sexual reproduction Meiosis vs. Mitosis Lab Mitosis • • • • • A process of cell division DNA is replicated in prophase Produces 2 identical cells Produces diploid cells (2N) Produces somatic (body) cells Meiosis • • • • • A process of cell division DNA is replicated in prophase Produces 4 different cells Produces haploid cells (1N) Produces gametes (sex cells)