Module 5 Cell Division
Lesson 3.5.4
Lesson 4—Meiosis
Get Focused
There is an urban legend that everyone on the planet has a double somewhere. Someone you could be mistaken for. Could you really have an identical double out there running around and you don’t know about it? Well, genetically it is impossible, unless you were an identical twin at birth and were separated. The reason for this variation in individuals is the focus of this lesson: cell division by meiosis. Unlike mitosis where daughter cells are nearly identical, cell division or chromosome separation by meiosis creates unique daughter cells called gametes. How unique? Well an average human male will create about 525 billion sperm (male gamete cells) over a life time and not one will be the same genetically. Recall from the previous unit that a sperm must fertilize an egg (female gamete cell) to create a new person, and you will begin to understand the impossibility of there randomly being exactly two of you! This part of our life cycle, the creation of gamete cells, is all about variation. This variation ensures the survival of a species, as you will come to appreciate in Unit D.
In this lesson you will learn to describe the stages of meiosis, you will come to understand when meiosis is necessary, as well as how it differs from mitosis. You will learn the major sources of genetic diversity, and why this is important to a species.
In this lesson you will examine the following focusing questions
- How does meiosis contribute to genetic variation?
- What differences exist between fraternal and identical twins?
This lesson will take approximately 120 minutes to complete.
Module 5: Lesson 4 Assignment
You will complete Investigation 16.C: Modeling to Compare Meiosis and Mitosis, and complete the online assignment cloning for assessment.
The other questions and activities in this lesson are not marked by the teacher; however, you should still attempt all of the work offered here. They are designed to help you review important information and build key concepts that may be applied in future lessons.