Student News

Molecule of the Week – Chlorophyll

Ivory Hills – November 9, 2011

The clocks have been set back an hour, there is a bracing chill in the air to greet you each morning and deciduous trees have nearly lost their last leaf.   Just a few weeks ago these leaves were still green with the vibrant color of chlorophyll.  It turns out that there are many related molecules that fall into the chlorophyll family (The illustration depicts ‘chlorophyll a’ for your viewing pleasure).  These compounds work cooperatively with a diverse array of other molecules to harness the energy in sunlight and produce sugars and oxygen from water and carbon dioxide.  The oxygen is essentially a waste product for the plant but we can’t live without it.

Why is chlorophyll green?  The portion of the molecule that performs some very important work can only do so after absorbing a photon from sunlight.  The light absorbed is orange-red in color.  Thus the green part of the spectrum is unabsorbed and able to be reflected to your eye (Test your understanding:  Would plants grow better with red light bulbs or green light bulbs?).  Humans have invented solar cells to try and capture energy from the sun but plants still do it better and they beat us to it.  There is still much to learn from the study of these fascinating organisms.  When spring finally returns to the valley, please take the time to marvel in the fact that each tree you meet will have millions of ‘green units’ quietly absorbing energy from the sun and creating part of the air we breathe.