Bio-Teen December. 2013 | Page 9

8.

What is it like to be an oxygen atom through photosynthesis?

By: Jenell Louissaint

Being an oxygen molecule can be pretty lonely sometimes, that was until I met my two friends. They were both hydrogen molecules, twins, and after we had our first meeting we were inseparable. We had made the strongest of bonds, the covalent, and became a water molecule.

We had been resting in a watering pot, until suddenly we were poured into the dirt of a huge tree. Next thing we knew, osmosis was bringing us to the chloroplast of a plant cell, and into the stroma. It wasn't soon until we realized we were going through the light-dependent reaction of photosynthesis. I could feel the heat of the sun giving energy to the electrons around us. An enzyme broke me and my friends apart turning them into two electrons, or two H+ ions, and me into once again a lone oxygen atom. I was eventually released out of the plant cell and into the air with another oxygen atom.

One of my friends now a H+ ion were taken from the stroma into the inner thylakoid. My other friend now an energized electron began to transport H+ ions. They were both then picked up by NADP+ and become NADPH. Other H+ ions stayed, making the thylakoid membrane positively charged, giving the energy to make ATP. The protein inside the membrane, ATP synthase, let the H+ ions go through the membrane, by spinning and then binding ADP and a phosphate group at the same

time.

My friends were taken into the Calvin Cycle, a reaction that produces high-energy sugars and does not require light. In came six carbon dioxide molecules, which combined with six five-carbon molecules to form twelve three-carbon molecules. Using NADPH made by my friends, and ATP energy; the carbon molecules were changed into high-energy forms. Two of the carbon molecules were made into three 3-carbon molecules, which formed sugars and other compounds. The rest of the carbon molecules were combined with new six carbon dioxide molecules and began the cycle again.

I never saw my friends again, but I am now surrounded with more atoms like me. I was just currently breathed in by a bear so we’ll see how that goes.