Introduction

Module 7 – The Cell Cycle, Mitosis, and Meiosis

Introduction

At this point in the semester, we have defined cells as the basic unit of life and we know that, as stated in the cell theory, all new cells come from pre-existing cells. We have examined the working parts of the cell, the nature of the molecules that compose the cell, the organelles found within the cell, how those organelles work together to produce proteins, lipids, and even (some) produce sugar and energy at the cellular level. For this next module, we will begin our work looking at the “life of a cell” or cell cycle in which we examine the steps needed to duplicate the contents of one cell so that one cell can undergo division (mitosis or meiosis) to produce new cells.

We will focus our work in this module on exploring the life cycle of animals and how/ when/ where duplication, division and fertilization take place. The animal life cycle is something you may already be familiar with. Think about what you already know:

Looking at the animal/ human life cycle: Can you name the first cell in the life cycle? What is the name of the first cell of a multicellular human being?

Since the cell theory states that all new cells come from pre-existing cells, where does this cell come from? Answer: The fusion of sex cells (the sperm and egg cell). Where do the sex cells come from? We will start with these questions and “follow the cell” through the cell cycle, and division (mitosis and meiosis).

Once we have completed this module, you should be familiar with the stages of the cell cycle, generally how long each stage takes to complete, and the stages of mitosis and meiosis.

Below are some questions that you should be able to answer following the completion of your work in this module:

  • When during the animal life cycle does this process occur?
  • For mitosis and meiosis, how many overall divisions will occur and what phases make up one division?
  • How many daughter cells will be formed and will those daughter cells be identical to the parent cell?
  • In addition, for meiosis, consider what processes contribute to genetic diversity in the sex cells that are produced and why genetic diversity is important in the first place 1 .

Learning Outcomes

This module addresses the following Course Learning Outcomes listed in the Syllabus for this course:

  • Demonstrate knowledge of biological principles.
  • Demonstrate knowledge of scientific method.
  • Communicate scientific ideas through oral or written assignments.
  • Interpret scientific models such as formulas, graphs and tables.
  • Demonstrate problem solving methods in situations that are encountered outside of the classroom 1 .

Module Objectives

Upon completion of this module, the student will be able to:

  • Define the following terms: gene , genome , chromosome , diploid , haploid , centrosome , homologous chromosome , cytokinesis ,interphase , cytoskeletal fibers , centromere , sister chromatids .
  • Define the cell theory (as stated in Module 3).
  • Describe the phases of the cell cycle (Interphase and the M phase) and what happens during each phase of the cycle.
  • State the general time frame that the cell spends in each of the phases of the cell cycle.
  • Define when mitosis and meiosis occur during the animal life cycle.
  • Define fertilization.
  • Name the cellular structures that are involved in the process of mitosis and meiosis.
  • Describe what happens during each of the phases within mitosis and meiosis.
  • Describe the differences in plant and animal cells in late telophase.
  • Describe binary fission in bacteria.
  • Describe crossing over and independent assortment.
  • Describe the problems that can occur during the cell cycle and how those changes will affect the cells that are produced 1 .