Module 5 Lesson 3 - 1
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Lesson 3 — Meiosis
Get Focused
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Do you think it is possible to have an identical double out there on the planet without you knowing about it? 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 identical, cell division or chromosome separation by meiosis creates unique daughter cells called gametes.
How unique? An average human male can produce about 525 billion sperm (male gamete cells) during his life time, but not one will be genetically the same as another. Recall from the previous unit that a sperm must fertilize an egg (female gamete cell) to create a new person, and you can begin to understand the impossibility of finding someone exactly like you!
The reason for this variation in individuals is the focus of this lesson: cell division by meiosis. Unlike mitosis where daughter cells are identical, cell division or chromosome separation by meiosis creates unique daughter cells called gametes.
How unique? An average human male can produce about 525 billion sperm (male gamete cells) during his life time, but not one will be genetically the same as another. Recall from the previous unit that a sperm must fertilize an egg (female gamete cell) to create a new person, and you can begin to understand the impossibility of finding someone exactly like you!
This part of our life cycle, the production 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 the reason this is important to a species.
In this lesson, you will examine these focusing questions
- How does meiosis contribute to genetic variation?
- What differences exist between fraternal and identical twins?