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Name: Peter
Status: Educator
Grade:  Other
Location: CO
Country: United States
Date: Summer 2010

If all cells in the human body contain the same strand of DNA, how does cells in different parts of the body know to function correctly? (i.e. how does a cell know that it is an eye cell and not a heart cell?)

Cells use a complicated set of signaling molecules that govern which proteins they express, and therefore which form and function they take. Cells can respond to a whole variety of compounds in minute, minute quantities, such as salts, proteins, hormones, and many more. Scientists are just scratching the surface on all the components that play a role, and how they all work together. Many scientists are working on figuring out the exact environment and recipe required to coax a cell to differentiate (turn into a different type of cell) into a desired form.

There is current research showing that undifferentiated stem cells can be stimulated with various substances to specialize into specific types of cells. However, once a cell differentiates, it may or may not be able to convert to a different kind of cell (usually it cannot). This is why stem cells are so interesting to scientists, because they can still differentiate into many other kinds of cells.

Hope this helps,

Different genes are expressed (turned on) in diferent cells.

Ron Baker, Ph.D.

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