Question

END-PRODUCT INHIBITION
(Please see attachment), then compare to this short explanation from the following webpage: http://www.occc.edu/biologylabs/Documents/Homeostasis/End_Product_Inhibition.htm

Answer 1

I do not understand how the example from the paragraph above is an example of end-product inhibiton.

Answer 2

;

Answer 3

@blues

Answer 4

End product inhibition is a molecular "open mouth, insert foot" way of controlling the concentration (in some cases) or the absolute amount (in others) of a particular molecular species. If there is a lot of Particle X around, the cell does not need any more of it, so Particle X downregulates the enzymes or other proteins involved in its own production.

In the context of a biosynthetic pathway, the product or one of the final products or later intermediates usually acts on the enzyme at the start of the pathway (several removed from the final product or later intermediate). This prevents the cell from committing to the biosynthetic process when it doesn't need to, which is more energetically efficient than committing, processing up to the final step and then saying, "Oops, we don't need any more of this after all" and then being stuck with all that semi-processed molecule lying around.

I think the sticky bit in this paragraph is that decreased catecholamine release means that less catecholamine leaves the cytosol, which means the concentration of catecholamine in the cytosol is actually higher. All this cytosolic catecholamine inhibits TH production, which in turn limits the production of more catecholamine in the cytosol. So it is a nice model of end product inhibition.

Hope that is helpful...?