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Name: 
Status: Educator
Grade:  6-8
Location: OH
Country: United States
Date: May 2005


Question:
Our science book tells us that lead poisoning is caused by the lead fooling cells into thinking that it is magnesium or calcium. We wanted to know how it fool's the cells into letting it in?



Replies:
"Fools" implies that lead takes an active role in a deception, but another way of looking at it is the cell is ineffective at distinguishing. Both lead and calcium can have a +2 charge as ions, and the ionic radius (how big the ion appears in solution) is somewhat similar. Because of the similarity, lead ions can easily be transported as though it were calcium. However, problems arise when some proteins bind the lead more tightly than they would calcium, altering or stopping the protein function, thus harming the cell. If it is just a few lead ions, the cell can make more proteins, but if it is a lot, the cell may not recover and can die.

Some cells encountering higher amounts of lead (or other toxic metals) will make special proteins especially designed to bind the lead to store it out of harm's way.

Don


Cellular pumps that are responsible for the absorption of Ca, are tricked into "thinking" that Pb ions are Ca ions.

Ron Baker, Ph.D.



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