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| the larger a cell becomes, the more demands the cell places on its DNA. in addition, the cell has more trouble moving enough nutrients and wastes across the cell membrane |
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| before it becomes too large, a growing cell divides forming 2 "daughter" cells. the process by which a cell divides into 2 new daughter cells is called cell division |
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| in eukaryotes, cell division is more complicated and occurs in 2 main stages. the first stage, division of the cell nucleus, is mitosis |
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| 2nd stage, division of the cytoplasm is cytokenesis |
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| each chromosome consists of 2 identical sister chromatids. when the cell divides the sister chromatids separate from each other. one chromatid goes to each of the 2 new cells |
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| each pair of chromatids is attached at an area called the centromere usually located near the middle of the chromatids, although some lie near the ends. a human body cell entering cell division contains 46 chromosomes, each of which consists of 2 chromatids |
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| series of events that cells go thru as they grow and divide. during the cell cycle, a cell grows, prepares for division, and divides to form 2 daughter cells, each of which then begins the cycle again. |
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| cell cycle is regulated by a specific protein called cyclin. amount of this protein in the cell rises and falls in time with cell cycle. cyclins regulate the timing of the cell cycle in eukaryotic cells |
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| proteins that respond to events inside the cell. allow the cell cycle to proceed only when certain processes have happened inside the cell |
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| proteins that respond to events outside the cell. direct cells to speed up or slow down cell cycle. |
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| it is the same except during cytokenesis. in plants, a structure known as the cell plate forms midway between the divided nuclei. the cell plate gradually develops into a separating membrane. a cell wall then begins to appear in the cell plate |
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| a disorder in which some of the bodys own cells lose the ability to control growth. cancer cells do not respond to the signals that regulate the growth of most cells. cancer cells divide uncontrollably and form masses of cells called tumors that damage surrounding tissues. cancer can spread causing serious medical problems or even death. |
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