Module 5

Module 5—Cell Division: The Processes of Mitosis and Meiosis

Big Picture

 

This module is about cycles. Our body cells all follow a cycle. No doubt, somewhere in your childhood, you skinned your knee or cut your finger. Once the tears were done and the bandage was applied, you were probably told it would eventually heal. Over time, our cells are constantly growing and dividing to replace what is old or damaged. Skin cells can replace themselves every three days. Cells of the digestive tract and respiratory tract replace themselves rapidly because of the damage they experience from everyday use. Muscle cells are much slower to replace, and bones can take months to heal.

 

Our life is part of a cycle too. In the previous unit you studied in detail how human life begins. In this module you will learn how other organisms may follow similar or very different patterns in reproduction. As you consider your own family, everyone is at a different stage in their life cycle, and so are the cells within their bodies.

 

What would happen if we could step outside of one of these cycles? What would it be like to get our cell lines to stop growing older? What if they could grow and reproduce at the same rate, throughout our lives, as when we are twenty years old? Aside from the social implications, there could also be very serious biological implications to consider. Cancer cells are in essence our own body cells that no longer respect the cell cycle. They reproduce as quickly as they can and never stop. Clearly, cancerous cells are not the target of the anti-aging industry! As you continue through this module, think about the internal clock that regulates your cell reproduction and aging.

 

As you explore healthy and unhealthy or uncontrolled cell cycles, you will focus on the big question of how cellular processes allow for growth, healing, and reproduction in the support of the survival of living organisms.

 

This module will explore the following focusing questions:

• What structures pass genetic information on to the next generation, and in what ways can cells ensure this information is passed on successfully?

• What are the stages and phases of the cell cycle, and do these change with age?

• How do meiosis and mitosis compare in the creation of new cells?
  
  
• When is consistency desired over variation, and which processes ensure the proper outcome?
  
  
• What differences exist between fraternal and identical twins?
  
  
• How do chromosome disorders occur, and why does their occurrence increase with age?
  
  
• What are the advantages or disadvantages of different reproductive strategies?

This module relies on prior knowledge of the cell and how it works. If you feel you need to review the concepts of the cell before you begin this module, read pages 546 and 547 in your textbook. If you are comfortable with your knowledge of the cell, continue on with the module.

 

To help you organize the concepts you learn in Module 5, and to provide you with a study aid for review before you complete the Module Assessment, you may choose to download the Concept Organizer for Module 5. Fill in this concept organizer with the ideas you master as you work through each lesson, or prepare the organizer when you have completed Module 5. You can use keywords, point form, or any amount of detail that meets your needs. You may choose to work from the file on your computer, print the document and work from the paper copy, or copy the outline onto a large sheet of poster paper. After you have prepared your concept organizer, you may wish to check your work with the concept organizer provided in the Module Summary. The concept organizer provided outlines some of the key topics that you should include in each lesson of your concept organizer. This is a great tool to review and use for study purposes, but using this organizer is completely your choice.

 

Your Module Assessment will involve the application of your knowledge about normal growth, repair, and reproduction in cells and organisms; consideration of exceptions to normal patterns; and evaluation of their impact. When you have completed all the lessons, you will need to complete one of the Module Assessment task options. For further details about the Module Assessment and the evaluation criteria, visit the Module Assessment section.

 

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