Chlorophyll << KLAWR uh fihl >> is the chemical pigment that gives plants their green color. It is also found in algae and certain bacteria. Chlorophyll absorbs light energy from the sun for use in photosynthesis. Photosynthesis is the process by which certain living things use light energy to make food.
In plants and algae, chlorophyll is found inside tiny structures within the cells known as chloroplasts. A single cell can carry a large number of chloroplasts. Inside each chloroplast are several flattened, disk-shaped structures called thylakoids that are stacked one on top of another. In photosynthesis, light energy is absorbed by chlorophyll and channeled to specialized reaction centers in the thylakoids. The reaction centers, along with electron-carrier molecules, convert the light energy to chemical energy. This chemical energy enables plants to use carbon dioxide from the air to make sugars and such other food substances as starch, fat, protein, and vitamins.
There are several forms of chlorophyll. The most common forms in plants are chlorophyll a and chlorophyll b. These different forms absorb most visible light, either in the form of long wavelengths—red rays—or short wavelengths, blue-violet rays. The middle wavelengths of light—green rays—are absorbed least effectively. Some bacteria have special chlorophylls that can absorb an invisible type of light called infrared rays for use in photosynthesis.
