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Learn about the fascinating process of cellular division and its importance in reproduction, growth, and repair. Discover how cells know when and how to divide through DNA instructions. Explore the three stages of the cell cycle: interphase, mitosis, and cytokinesis, and understand the role of chromosomes, centromere, and sister chromatids. Delve into the specific events of each phase of mitosis - prophase, metaphase, anaphase, and telophase. Finally, grasp the concept of cytokinesis, where the cytoplasm divides and one cell becomes two.
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Cell Division Why do cells divide? • Reproduction • Growth • Repair How does the cell know how to divide? The DNA has the instructions for all of the cell’s activities.
Cell Cycle The sequence of development and division of a cell 3 Parts • Interphase - Preparation • Mitosis – Cell division • Cytokinesis – Splitting • Adult human cell: ~24 hrs • 18-20 hours in interphase • 2 hours in mitosis • Embryonic cells: 30 min. How long does it take?
Interphase What happens • Cell doubles in size • DNA replicates • Organelles double in number
The role of chromosomes centromere sister chromatids
Sister chromatids are joined by a centromere (forms an “X”)
Mitosis: PROPHASE What happens • DNA forms chromosomes • Spindle forms • Centrioles move toward opposite poles • Nuclear membrane begins to disappear
Mitosis: METAPHASE What happens • Nucleus has disappeared completely • Chromosomes line up in the middle of the cell “equator”
Mitosis: ANAPHASE What happens • Centromeres divide • Chromatids separate and move to opposite poles
Mitosis: TELOPHASE What happens • Nuclear membrane forms around each group of chromosomes • Chromosomes unwind • Cytokinesis begins
Cytokinesis • Cytoplasm divides • One cell becomes 2 cells What happens