Cell Cycle: Mitosis & Meiosis

*Enduring understanding 3.A: Heritable information provides for continuity of life.

-Essential knowledge 3.A.2: In eukaryotes, heritable information is passed to the next generation via processes that include the cell cycle and mitosis or meiosis plus fertilization.

• a. The cell cycle is a complex set of stages that is highly regulated with checkpoints, which determine the ultimate fate of the cell. Evidence of student learning is a demonstrated understanding of each of the following:
  • 1. Interphase consists of three phases: growth, synthesis of DNA, preparation for mitosis.
  • 2. The cell cycle is directed by internal controls or checkpoints. Internal and external signals provide stop-and-go signs at the checkpoints.
  • 3. Cyclins and cyclin-dependent kinases control the cell cycle.
  • 4. Mitosis alternates with interphase in the cell cycle.
  • 5. When a cell specializes, it often enters into a stage where it no longer divides, but it can reenter the cell cycle when given appropriate cues. Nondividing cells may exit the cell cycle; or hold at a particular stage in the cell cycle.
• b. Mitosis passes a complete genome from the parent cell to daughter cells. Evidence of student learning is a demonstrated understanding of each of the following:
  • 1. Mitosis occurs after DNA replication.
  • 2. Mitosis followed by cytokinesis produces two genetically identical daughter cells.
  • 3. Mitosis plays a role in growth, repair, and asexual reproduction
  • 4. Mitosis is a continuous process with observable structural features along the mitotic process. Evidence of student learning is demonstrated by knowing the order of the processes (replication, alignment, separation).
• c. Meiosis, a reduction division, followed by fertilization ensures genetic diversity in sexually reproducing organisms. Evidence of student learning is a demonstrated understanding of each of the following:
  • 1. Meiosis ensures that each gamete receives one complete haploid (1n) set of chromosomes.
  • 2. During meiosis, homologous chromosomes are paired, with one homologue originating from the maternal parent and the other from the paternal parent. Orientation of the chromosome pairs is random with respect to the cell poles.
  • 3. Separation of the homologous chromosomes ensures that each gamete receives a haploid (1n) set of chromosomes composed of both maternal and paternal chromosomes.
  • 4. During meiosis, homologous chromatids exchange genetic material via a process called “crossing over,” which increases genetic variation in the resultant gametes. [See also 3.C.2]
  • 5. Fertilization involves the fusion of two gametes, increases genetic variation in populations by providing for new combinations of genetic information in the zygote, and restores the diploid number of chromosomes.
    • Learning Objectives:
      • LO 3.7 The student can make predictions about natural phenomena occurring during the cell cycle. [See SP 6.4]
      • LO 3.8 The student can describe the events that occur in the cell cycle. [See SP 1.2]
      • LO 3.9 The student is able to construct an explanation, using visual representations or narratives, as to how DNA in chromosomes is transmitted to the next generation via mitosis, or meiosis followed by fertilization. [See SP 6.2]
      • LO 3.10 The student is able to represent the connection between meiosis and increased genetic diversity necessary for evolution. [See SP 7.1]
      • LO 3.11 The student is able to evaluate evidence provided by data sets to support the claim that heritable information is passed from one generation to another generation through mitosis, or meiosis followed by fertilization. [See SP 5.3]