Mitosis is one process of cell division that produces two genetically identical daughter cells from one parent cell. It is the most common way cells divide. In this activity, students will create a storyboard that models the stages of mitosis from start to finish. Students should be sure to provide a description of what happens at each stage along with a visual representation. For an alternate activity, print out the example storyboard, cut the cells out, and have students put the steps in the correct order.
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Student Instructions
Create a storyboard showing the process of mitosis.
Begin the lesson with an introduction to genetic disorders, emphasizing how they can arise from errors during meiosis. Discuss common disorders such as Down syndrome, Turner syndrome, and Klinefelter syndrome, explaining their chromosomal basis. Introduce the stages of meiosis, highlighting where and how errors can occur, such as non-disjunction or translocations.
Guide students to research specific genetic disorders that are a result of meiotic errors. Provide resources such as textbooks, scientific articles, and reliable online sources. Encourage them to explore the causes, symptoms, and impacts of these disorders. During this phase, students should gather information that they will later illustrate in their storyboards.
Students begin creating their storyboards, illustrating how meiotic errors lead to the genetic disorders they researched. Encourage them to include detailed illustrations of the meiosis stages, indicating where the errors occur, and how they result in the specific chromosomal abnormalities associated with their chosen disorder. Provide art supplies for traditional storyboards or access to digital tools for electronic versions.
Have students present their storyboards to the class, explaining the process of meiosis, the specific error they focused on, and how it leads to the genetic disorder. Follow each presentation with a class discussion, allowing for questions and clarification. This not only reinforces the material but also enhances understanding through peer learning.
Mitosis is divided into distinct phases, each with specific cellular events. In Prophase, chromosomes condense and become visible, the nuclear envelope breaks down, and the spindle apparatus begins to form. During Prometaphase, the nuclear envelope is completely dissolved, and spindle fibers attach to chromosomes. Metaphase is characterized by the alignment of chromosomes along the metaphase plate at the cell's equator, preparing them for equal segregation. In Anaphase, sister chromatids are pulled apart by the spindle fibers and move toward opposite poles of the cell, now considered separate chromosomes. Finally, Telophase involves the reformation of the nuclear envelope around each set of chromosomes at the poles, the chromosomes begin to de-condense, and the spindle apparatus disassembles. These phases ensure that each daughter cell receives an identical set of chromosomes, crucial for maintaining genetic stability across cell generations.
Errors during mitosis can lead to serious consequences. If chromosomes do not segregate equally into the daughter cells, it results in aneuploidy, where cells have an abnormal number of chromosomes. This can cause genetic disorders and is often seen in cancer cells, where abnormal numbers and structures of chromosomes are common. Errors in spindle formation or attachment can also lead to improper chromosome segregation. In developmental stages, mitotic errors can lead to miscarriages or congenital abnormalities. On a cellular level, such errors can trigger cell death or senescence (a state of permanent cell cycle arrest), acting as safeguards to prevent the proliferation of genetically abnormal cells.
Mitosis occurs in eukaryotic cells, which include a vast array of cell types in multicellular organisms, like animals, plants, and fungi. However, not all cells undergo mitosis. For example, mature nerve cells and muscle cells in humans often enter a state called G0 phase, where they do not divide further. On the other hand, cells in tissues like skin or the lining of the gut are constantly dividing through mitosis. In contrast, prokaryotic cells, such as bacteria, do not undergo mitosis; instead, they replicate through a process called binary fission, which is simpler but serves a similar purpose of distributing genetic material into daughter cells. Thus, while mitosis is widespread across many cell types in multicellular organisms, its occurrence is specific to the needs and type of the organism.