What Is Photosynthesis?
The green leaves of plants perform an intricate chemistry called photosynthesis, which is fundamental to life on earth. It provides both our food and the oxygen we need to breath.
When carbon dioxide from the air combines with water from the soil to make simple carbohydrates, photosynthesis occurs. Carbohydrates, which are the compounds of carbon and hydrogen, are precursors of sugars such as glucose, fructose, and sucrose. And the by-product of photosynthesis is oxygen.
So, in actuality, photosynthesis begins the transformation that turns inorganic, or non-living molecules into organic ones--the ones associated with life. Life-supporting oxygen is produced in the bargain. Photosynthesis needs the power of light to drive it. This power comes from the radiant energy of the sun.
The way plants can accomplish photosynthesis is by having certain substances or catalysts, that initiate and guide this process along. The green pigment chlorophyll, the substance that gives plants their green color, is the most significant of these substances. However, photosynthesis also works with certain nongreen substances, such as the pigment phycobilin in red algae. Sometimes the green chlorophyll is masked by nongreen pigments such as carotene, which help capture the light and forward it to chlorophyll pigments. (As in the leaves of the copper beeches.)
Simple carbohydrate sugars, which are the primary organic products of photosynthesis, are then worked upon by a battery of plant enzymes, which are special proteins. These special enzymes activate processes that make simple carbohydrate molecules grow in size and complexity.
In the miniature chemical laboratories of living plant cells, a great variety of organic compounds are produced, some transported to the fleshy roots or tubers, through the plants stem, where it gets stored as complex carbohydrates such as starch.
Other simple carbohydrates are transformed into cellulose and lignin. These form the tough walls of plant cells, giving the plant its supporting skeleton.
When the carbohydrates combine with nitrates (nitrogen, hydrogen, and oxygen) and other chemical elements, they form more complex organic compounds. The most important of these complex compounds are the amino acids, the building blocks of all life’s proteins. Other carbohydrate molecules are rebuilt and recombined to form fatty acids, which are the building blocks of the fats and oils found in plants.
Within all plant cells chemical reactions proceed silently and persistently. The process of photosynthesis is fundamental to life on earth, for it not only provides our food, but the oxygen we need to breath as well.