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Stimulation of Cell Replication

Why do different kinds of cells require different signal receptors to proceed through mitosis? In a multicellular organism many different kinds of cells undergo mitosis. Mitosis occurs during the growth and development of the organism. Mitosis also occurs during the healing of injuries and the natural replacement of cells. The cell cycle is controlled by the activation and repression of molecules at various checkpoints. Control is ultimately caused by signals from external sources, cells in other tissues for example. Different cell types have different receptors to stimulate mitosis and cell division. Coordination of growth, development, and maintenance of the body often requires cell types to divide more frequently than others. Each cell type will need different receptors so that its rate of mitosis is not dependent on the rate for other cell types.

View the animation below, then complete the quiz to test your knowledge of the concept.






1Growth factor receptors are typically found in the
A)cell membrane.
B)cytoplasm.
C)nucleus.
D)mitochondria.
E)Golgi apparatus.



2The growth factor-receptor complex initiates
A)DNA replication.
B)mRNA transcription.
C)protein synthesis.
D)protein kinase cascades.
E)protein breakdown.



3Proteins that stimulate cell division include
A)caspases.
B)cyclins.
C)cyclin-dependent kinases.
D)caspases and cyclins.
E)cyclins and cyclin-dependent kinases.



4Animal cells divide usually only when specific growth factors are present.
A)True
B)False



5There are only a few types of growth factors.
A)True
B)False







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