My_Ch12_lecture_Mitosis(2009030423480766)

My_Ch12_lecture_Mitosis(2009030423480766) - Chapter 12 The...

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http://www.gocomics.com/inthebleachers/2006/10/18/ Purpose: to understand the cell cycle, cell division, and to realize that mitosis is just a small part of the cell’s life cycle. Know the stages of mitosis. Understand how the cell cycle is regulated. (AP Biology Major themes: IV- Continuity and Change, V-Structure & Function, VI- Regulation) What you MUST know in Ch 12: Phases of the cell cycle Events in mitosis Cytokinesis in plants vs. animals Binary fission vs. mitosis Checkpoints Cyclins This chapter should be review for you; although as usual there are some new details to know.
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Cell Division “Every cell from a cell.” One of the defining characteristics of living organisms, the ability to reproduce , is due to the ability of cells to divide Growth of multicellular organisms from a single cell (zygote) Repair and replacement of cells that are damaged or dead, by making a genetically identical cell = mitosis (“t” in mitosis = “twin” cells) Why do cells divide? o To maintain a high surface-to-volume ratio A large surface area (plasma membrane) relative to the cell volume allows the cell to efficiently exchange its contents (wastes) with the environment, and to take in environmental molecules (nutrients, oxygen) by diffusion or active transport. If the surface area is too small to accomplish this, exchange will not occur efficiently enough to sustain the cell. o To maintain an adequate genome-to-volume ratio genome = all of a cell’s DNA a finite (limited) amount of DNA is available to code for all the proteins a cell needs (which directs virtually all cell activities) If there is too little DNA for too large a cell, the DNA will not have the capacity to regulate all of the cell’s activities. DNA Chromatin = DNA-protein complex, exists in a long, thin fiber in interphase . o Chromatin is contained in the nucleus
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Chromatin condenses (becomes more tightly coiled) into chromosomes in prophase Each chromosome is made of 2 identical halves (replicated during the S phase of interphase), called sister chromatids , which are connected to each other at the centromere. Each chromatid = 1 single molecule of DNA Each sister chromatid has a kinetochore
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My_Ch12_lecture_Mitosis(2009030423480766) - Chapter 12 The...

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