Expert: Joy Ramos - 4/24/2006

Question
In plant photosynthesis, I know that "carbohydrate" is the food for the plant, and the "oxygen" keeps the plant living, cause, the oxygen comes from the air.

My question is:

1) What does Enzymes do in Photosynthesis/ or what is its overall role?

2) Where does Chlorophyll and enzymes come from?

3) How is carbohydrate and oxygen and chlorophyll and enzymes used in Cellular respiration?

Answer
Hi, Nick. Enzymes in photosynthesis use light to convert Carbon dioxide in the air plus water to produce carbohydrates and oxygen.

I'm not exactly sure how chlorophyll and other enzymes came about but I believe it first appeared in ancient organisms that survived through time because of the significant advantage these proteins gave them in terms of producing energy.

When you interpret "respiration" in the strictest sense, that process involves using up oxygen and other energy sources (carbohydrates, etc) to produce energy (ATP). Chlorophyll and other photosynthetic enzymes, however, CAN lead to consumption of oxygen instead of producing it in a process called "photorespiration".  The pathway is a complicated one and invovles enzymes such as phospho-glycolate phosphatase inside the chloroplast (probably not the chlorophyll), plus other enzymes found in the peroxisome and the mitochondria.

Hope this helps!