AP Biology chapter 9 cell division

Pregunta	Respuesta
Why do cells divide? (4)	-replace dead or damaged cells -growth of multicellular organisms (making more cells) -reproduction -"DNA overload
Mitosis functions in	Growth
DNA and proteins Packaged as chromatic	-euchromatin: lightly packaged (de condensed) -heterochromatin: tightly packaged (condensed)
Interphase (4)	•growth •normal cell functions •chromosomes copied •prepare to divide
Anchorage dependence	•most cells divide only when attached to a surface
Density-dependent inhibition	•cells continue dividing until they touch one another then stop
Internal regulators	•cycling increase causes cell to divide
Internal regulator : p53 gene	Halts cell cycle until DNA is repaired
External regulators	•growth factors (growth hormones) -proteins secreted by cells that stimulate other cells to divide -signal cell to divide
Checkpoints	Help regulate the cell cycle
Cancer cells	-Have abnormal cell cycles -caused by mutant genes regulating the cell cycle (p53 gene) -ignore checkpoints and other regulatory mechanisms -divide excessively, can form tumors
Malignant tumors	Can invade other tissues and may kill the organisms

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	Creado por Kimberlee Hernandez hace casi 8 años