How do plants turn towards light?

taguebw at taguebw at
Mon Feb 3 12:30:44 EST 1997

Fredrik Loenn wrote:
Me and my
> girlfriend (who's a chemist and say's she knows better) have been
> discussing something....

> Plants turn towards the sun (or other illumination), because the cells not exposed to the light, split more quickly. This makes the plant bend against the light.
> Is this idiotic, as my girlfriend says? In that case: What makes them
> turn and bend, the way they do?
> Regards,
> Fredrik Lonn

This is not idiotic. Actually though, the cells do not split (that is 
divide into two cells) but individual cells elongate (or grow) 
differentially on the side away from the light. This causes the curve 
toward light. 

Not to get into too many details, but the affect is due to the 
redistribution of the plant growth hormone auxin *away* from the side 
the light is shining on.

My 2 electrons....

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