The Purpose of Meiosis and Mitosis

1. The Purpose of Meiosis and Mitosis Bell work: Which one of Mr. Morgan’s parents does he look more like? Does he look identical to either one? Why?

2. 1. What do you think the word “diploid” might mean? • Let’s break the word apart. Di=TwoPloid=copies • We use the word diploid to describe a cell that has two almost identical chromosomes. With the exception of sex cells, almost all of a human’s cells are diploid. We must have diploid cells to function. • In regards to a human we must have a pair of chromosomes to function. With that in mind, what is something that is paired that you might use in your everyday life?

3. Example: The tongs of a tweezers. There are two of them and they must be almost identical in order to function properly. • Now, it’s your turn. Give me an example of something that is diploid. Be ready to share with the class

4. 2. What do you think the word “haploid” means? • Let’s break the word apart. • Hapl=single Ploid=copies • We use the word haploid to describe a cell that has only one chromosome. In its single, halved form it becomes called a chromatid. Haploid cells with their chromatids are found in human sex cells (sperm and egg cells). You started out as a combination of one haploid cell from your mom and one haploid cell from your dad.

5. In regards to a human, a haploid cell must join with another haploid cell to make a human. With that in mind, what is something that must be paired to make it functional? • Example: A single shoe. A shoe must be paired with another one to make the shoes functional. • Now it’s your turn. Give me an example of something that is haploid. Be ready to share it with the class.

6. 3. What does a diploid cell look like? • Write in your own words one thing you know about the word diploid. • A diploid cell with one chromosome will look like: On your slates, draw what a diploid cell with 3 chromosomes would look like.

7. Diploid Cell With 3 Chromosomes 3 1 2

8. 4. What does a haploid cell look like? • Write in your own words one thing you know about the word haploid. • A haploid cell with one chromatid will look like: On your slates, what would a haploid cell with 3 chromatids look like?

9. Haploid Cell With 3 Chromatids 1 2 3 On your slates, what would a triploid cell with one chromosome look like?

10. 5. What do meiosis and mitosis look like? • Mitosis: starts with a diploid cell and ends with 2 diploid cells.

11. Based on the following description, what does meiosis look like? Hint: fill in the chart. In this case, consider the start cell to only have one chromosome. • Meiosis: begins with one diploid cell and ends with 4 haploid cells.

12. 6. What are the purposes of meiosis and mitosis? • Keep that flow chart in mind as you watch the following video. Think about how meiosis and mitosis look relates to what their purpose is. Answer these questions. • a.What is the purpose of mitosis? • b.What is the purpose of meiosis? Video: http://www.youtube.com/watch?v=2aVnN4RePyI

13. In Class Assignment/Homework • In class assignment: Looking at the flow chart for meiosis and mitosis, how do the purposes of each process relate to their end results. Write 4-5 sentences relating form to function for both meiosis and mitosis. • *If you do not finish this in class, it will be done as homework and turned in tomorrow.