Rucete ✏ Biology In a Nutshell
1. What Is Mitosis?
- Mitosis is the process in which the nucleus of a eukaryotic cell divides, producing two genetically identical daughter nuclei.
- It ensures equal distribution of chromosomes.
2. Phases of Mitosis
Prophase
- The nucleolus disappears.
- Chromatin condenses into sister chromatids.
- The mitotic spindle begins to form in the cytoplasm.
- Microtubules extend from MTOCs (microtubule-organizing centers).
- The nuclear envelope breaks down.
- Microtubules attach to kinetochores of chromatids.
Metaphase
- Sister chromatids align at the metaphase plate (center of the cell).
- This alignment ensures equal division.
Anaphase
- Sister chromatids separate, becoming individual chromosomes.
- Chromosomes are pulled to opposite poles by the spindle apparatus.
Telophase
- New nuclear envelopes form around the separated chromosomes.
- Nucleoli reappear, and chromosomes decondense.
3. What Is Cytokinesis?
- Cytokinesis is the process of dividing the cytoplasm to form two separate daughter cells, following mitosis.
4. Cytokinesis in Plant Cells
- Golgi vesicles accumulate between the two forming nuclei.
- Vesicles fuse to form a cell plate.
- The cell plate develops into new plasma membranes and a cell wall.
5. Cytokinesis in Animal Cells
- Microfilaments form a contractile ring around the center of the cell.
- The ring contracts, forming a cleavage furrow that pinches the cell into two.
6. Interphase
- The phase before mitosis, where the cell grows and replicates its DNA.
- Subphases: G₁ → S → G₂
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Biology in a nutshell