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Questions and Answers
What is the primary function of mitosis in a cell?
Which phase of the cell cycle is the longest?
What structural change occurs to chromosomes during prophase?
What is the role of the kinetochore in mitosis?
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During metaphase, where do the chromosomes align?
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How do spindle fibers function in cells that do not possess centrioles?
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Which type of spindle fiber is directly linked to the kinetochores?
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What happens to the nuclear envelope during prophase?
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Study Notes
Mitosis Overview
- Mitosis is the process of nuclear division, resulting in two daughter cells with identical chromosome sets.
- Chromosome duplication is essential for mitosis to occur.
Prophase
- Prophase accounts for about 80% of the time taken for cell division, making it the longest phase.
- The cytoskeleton is dismantled to reform a new structure, increasing cytoplasm viscosity.
- Chromosomes condense into visible filaments as nucleolus material disperses within the nucleus.
- The nuclear envelope breaks down, producing membranes similar to the endoplasmic reticulum, allowing chromosomes to interact with the cytoplasm.
- Each sister chromatid possesses a kinetochore, a protein ring that connects to the microtubules of the mitotic spindle.
- Sister chromatids originate from the same chromosome and are held together by the centromere during early mitosis.
Metaphase
- Centrioles separate and migrate to opposite poles, facilitating the formation of spindle fibers.
- Kinetochore fibers attach spindle microtubules to the kinetochores on chromosomes.
- Polar fibers extend from centriole to centriole, not attaching to kinetochores.
- Astral fibers are positioned outward, supporting spindle structure.
- Chromosomes align at the cell's equator on the metaphase plate, held in place by spindle fibers connected to their centromeres.
- In plant cells, spindle fiber orientation is guided by the plasma membrane and cell poles, as they lack centrioles.
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Description
Dive into the intricacies of mitosis, focusing on the prophase stage. This phase represents 80% of the cell division duration and involves critical processes like chromosome duplication and cytoskeleton dismantling. Test your understanding of cell division with this quiz!
