meiosis

• Meiosis


  A type of cell division that reduces the number of chromosomes
• Gametes


  Sex cells that have half the number of chromosomes
• Haploid


  A cell with n number of chromosomes
• Diploid


  A cell that contains 2n number of chromosomes
• Sex chromosomes


  Chromosomes that determine an individual's gender
• Autosomes


  The other 22 pairs of chromosomes that are not sex chromosomes
• Meiosis I


  1. Interphase

  2. Prophase I

  3. Metaphase I

  4. Anaphase I

  5. Telophase I
• Crossing over


  A process during which chromosomal segments are exchanged between a pair of homologous chromosomes
• Meiosis II


  1. Prophase II

  2. Metaphase II

  3. Anaphase II

  4. Telophase II
• Meiosis provides genetic variation through independent assortment of alleles during gamete formation
• Asexual reproduction


  Chromosome number is maintained by mitosis, the organism inherits all of its chromosomes from a single parent, the new individual is genetically identical to its parent
• Telomeres


  Chromosomes that end in protective caps that consist of DNA associated with proteins
• Karyotype


  A type of micrograph in which the pairs of homologous chromosomes are arranged in decreasing size
• Nondisjunction


  Cell division during which sister chromatids fail to separate properly, can result in extra copies of certain chromosomes or only one copy of a particular chromosome in offspring
• Down syndrome


  Result of an extra chromosome 21, often called trisomy 21
• Turner's syndrome


  Individual has only one sex chromosome, results from fertilization with a gamete that had no sex chromosome
• Klinefelter's syndrome


  Individual has three sex chromosomes, results from fertilization with a gamete that had two sex chromosomes
• Cellular differentiation


  The process by which an unspecialized cell develops into a specialized cell with a defined structure and function
• Stem cells


  A type of cell that can be directed to become a specialized cell
• Embryonic stem cells


  Unspecialized cells that result after a sperm fertilizes an egg, each has all the DNA needed to develop into a wide variety of specialized cells
• Adult stem cells


  Stem cells found in various tissues in the body that can differentiate into the specific types of cells they are surrounded by