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Factors affecting the rate of mitosis
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Factors affecting the rate of mitosis:
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Cell size: large cells have a large distance between organelles, efficiency of chemical
processes is reduced. Large size is a key stimulus for mitosis
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It is controlled by enzymes so factors affecting enzyme activity affect mitosis
(temperature, pH, concentration of enzymes, concentration of substrate (raw
material), presence of poisons)
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DNA is replicated before mitosis. DNA controls production of enzymes so factors
affecting DNA affect mitosis (specifically mutagens such as alcohol, ionising
radiation)
Mitosis rate is high during times & places of growth and repair / cell replacement:
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germination in seeds (after dormancy is broken)
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seasonal growth in plants
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embryo growth, puberty, infancy/childhood
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root / shoot tips
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hair follicles
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bone marrow – blood cells are continuously being made
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skin cells – continuously replaced
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mucous membranes
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sites of damage eg wounds
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cancer (unregulated cell division)
Mitosis rate is low during times of dormancy, stasis, low growth:
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Seeds, winter for plants, some animals eg kangaroo can halt embryo development,
plant xylem cells are dead, skeletal muscle cells and nerve cells usually don’t divide
after they mature..
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