Module 5 Cell Division

Unit C Introduction

From one generation to the next, from single cell bacteria to people, we are all part of a competition to create more of our own species. How do we ensure our best is passed on to the next generation? Now that science has discovered most of the mechanics of the process of inheritance, a new question is arising; should we now manipulate inheritance to suit our whims? Should we have the power to decide exactly what the next generation will look like? This unit is all about the cycle of life. From the secrets of cellular reproduction, to the story of why you may have your grandmother’s nose, this unit will explore how our biology is caught in an increasingly complex drive to survive.

In Unit A you examined how the human body used the nervous or endocrine system to maintain homeostasis. In Unit 2 you examined closely how the human reproductive system ensured the continuation of our species.

There are three modules in Unit C: modules 5, 6 and 7.

In Module 5, you will again examine reproduction, but this time at the cellular level. Individual cells, like humans and all other multi-cellular organisms, need to ensure the next generation has all that it needs to survive and excel. In human reproduction, you saw how this creates a cycle as one is born, grows, mates, and gives birth to the next generation. In a similar way, cells follow a life cycle of growth, preparation, and division. In this unit, you will learn how the cell life cycle naturally progresses. You will examine how cells copy their instructions for the next generation. You will also discover how cells divide to form new, complete cells, or divide to form incomplete cells that must find another cell with which it will join in order to become a new, whole organism. You will compare these methods of reproduction, examining their advantages and limitations. As you work through this unit, you will begin realize just how important the regulation of the cell cycle is as you consider cancerous or “wild” cell growth.

In Module 6, you will come to understand that the instructions copied by cells during the cell cycle code for traits observed in organisms. You will look more closely at how an organism passes on his/her traits to the next generation. As you consider these patterns of inheritance, you will learn about the works of Gregor Mendel and Thomas Morgan and how they contributed to our understanding of genetics today. You will practice using predictive tools that will allow you to understand and explain the movement of a disease or condition through a family pedigree.

In Module 7, you will examine the molecular basis for these traits in the cell, and you will gain an understanding of how cells express these traits through protein synthesis. As you examine the molecules present in our cells, you will reflect on how mutation can change the intended expression of our genetically inherited traits. Genetic change can result in disease. It can also result in enhanced abilities, and can be the basis of evolution as explored in Unit D.

The major concepts you will explore and the skills you will develop in this unit are:

• Explain the rules and steps involved in mitosis and meiosis that regulate the transmission of genetic information from one generation to the next.
• Describe the similarities and differences that exist in mitosis and meiosis that allow for growth, healing, and reproduction of organisms.
• Hypothesize how the understanding of the molecular nature of genes and DNA can help explain the transmission of traits, and how mutation at the molecular level results in changed proteins.
• Analyze how the knowledge of the molecular nature of genes and DNA has led to new biotechnologies and treatment of genetic disorders.

Think about the following questions as you complete this unit:

• What are the cellular processes that an organism uses for growth, healing, and reproduction to ensure the survival of his/her species?
• What regulates the transmission of genetic information from one generation to the next?
• How is DNA responsible for the production of proteins?
• How has the molecular knowledge of genes and DNA led to new biotechnologies and the treatment of genetic disorders?