Module 5 Lesson 1 - 1

Get Focused

Life is about cycles. At the cellular level, the cell cycle involves reproducing identical cells through mitosis. At the organism level, mitosis can again produce identical cells; this time, they reproduce their offspring. Organisms with variations are produced through meiosis, another type of cell cycle. The similarities and differences in the offspring can be explained by examining chromosomes.

Sometimes in nature, reproduction can be quite diversified and unique. Aphids all hatch from their eggs as female. Perhaps more alarming is the fact that they already have live nymph aphids developing inside. These, too, will be born female and pregnant. In very little time, aphids can dominate a crop and cause serious economic damage. This seems to be a winning reproductive strategy. Where are the male aphids, and what is their role? In the autumn, males are born. They mate with females and produce eggs that hatch over winter. Why does this change in the reproductive strategy occur? Why do aphids go through all the trouble of changing strategies when conditions are becoming more difficult?

In this lesson, you will identify the types of cellular division and reproduction and understand their functions and purpose. You will be able to recognize the structures within the cell that carry genetic information. You will learn about the significance of the number of chromosomes in cells, and you will learn to read a picture of human chromosomes.

This lesson examines the following focusing questions: 

• What kinds of cell division occur, and when are they used?
• What are the structures that pass genetic information to the next generation, and how are they observed?

Review

This chapter relies on prior knowledge of the cell and how it works. Please review the cell biology section before you begin this module by reading pages 546 and 547 in your textbook.

Review the various parts of a cell by studying the diagram on page 547 or try this Cellular Structures Gizmo

Read carefully through the Student Exploration Guide and follow the steps as described.

If you are comfortable with your knowledge of the parts of the cell, continue with the lesson.