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Name: Laura
Status: Student
Grade:  9-12
Location: OR
Country: United States
Date: April 2005


Question:
Could you explain why the cells on the edges of the colony would be in the log phase of the growth curve while the cells in the center of the pile would be in either the stationary or death phases.



Replies:
My guess would be that there is a higher concentration of nutrients in the medium at the edge of the colony because there are fewer cells per square cm in that area.

Ron Baker, Ph.D.


Remember that bacteria divide by binary fission, ie. the parent cell splits in half. So let's say there is one organism in the center of a plate. It divides into two and they divide into two, etc. As more cells are made, they spread out. So the cells in the center of the plate are "older" than those that have just divided on the edge. So, yes, there can be cells in different stages on the plate (or liquid culture).

vanhoeck



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