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Chapter 10: Mitosis Cell Growth and Division. Cell Division. Cell Division – cell divides into two new IDENTICAL “daughter cells” Mitosis – division of nucleus during eukaryotic cell division Cytokinesis – division of cytoplasm during eukaryotic cell division. Cell Cycle. Interphase.
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Cell Division • Cell Division – cell divides into two new IDENTICAL “daughter cells” • Mitosis – division of nucleus during eukaryotic cell division • Cytokinesis – division of cytoplasm during eukaryotic cell division
Interphase • Interphase • portion of cell cycle between divisions • ~ 75 – 80% life of cell • 3 phases: • G1: cells grow and develop • S: chromosomes replicate • G2: organelles required for division reproduce
Chromosome • Chromosome • located in nucleus • contains DNA • Chromatid • half of chromosome that has been replicated • pair of “sister” chromatin • Centromere • area where each pair of chromatids attach (in center) CHROMOSOME sisterchromatid centromere sisterchromatid
Mitosis Prophase Metaphase Anaphase Telophase “Please Make Another Test” • 1. Prophase • doubling of chromosomes & organelles • centrioles visible • 2. Metaphase • chromosomes line-up in the middle • spindles from centrioles connect to each chromatid (half of chromosome) • 3. Anaphase • chromatids are pulled apart to separate ends • membrane begins to pinch off in the middle • 4. Telophase • Nucleus and nuclear envelope reform • Chromosomes decondense and disappear (you can no longer see them) • Cytokinesis - complete division of cytoplasm • two daughter cells formed
Prophase • DNA condenses into chromosomes • Nuclear membrane begins to break down • - centrioles & chromosomes visible
Metaphase • - chromosomes line-up in the middle • - spindles from centrioles connect to each chromatid • Spindle • microtubules that help separate chromosomes
Anaphase • - chromatids are pulled apart to separate ends • - membrane begins to pinch off in the middle
Telophase • Each set of chromosomes is positioned at each end of the cell • Chromosomes begin to uncoil & spindles far apart • - two daughter cells formed Cytokinesis - cells “pinch” off from one another - cytoplasm divides
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Regulating the Cell Cycle • Cyclins • Proteins that stimulate division during growth and repair (Interphase) • Internal regulators • respond to the events inside the cell • External regulators • speed up or slow down the cell cycle
Cancer • Cancer = uncontrolled cell growth • do not respond to signals that regulate growth • causes: heredity, chemicals, radiation • Tumors = unregulated cell growth • Benign: cells stay together • Malignant: cells spread and grow elsewhere - invade healthy tissues