Why Does Light Affect Photolysis?
- Plant metabolism processes involve a series of chemical reactions that begin when light makes contact with plant leaves, according to Estrella Mountain Community College. Also known as photosynthesis, these processes rely on the energy contained in light to initiate this series of chemical reactions. The physical characteristics of light, or light waves enable them to alter the chemical processes that take place inside plant leaf cells. Photolysis occurs as leaf cells respond to the energy provided from light waves.
- According to Estrella Mountain Community College, visible light is a form of energy that exists within the electromagnetic spectrum. The electromagnetic spectrum represents different forms of energy as they exist within the physical world. Radio waves, microwaves and visible light waves are a few of these energy forms. Light travels in waves, or frequencies and contains both wave and particle properties. The wave property enables light to travel through materials, while the particle properties holds the actual energy contained inside the wave. In effect, plant leaves can absorb these light waves while the energy contained inside light particles transfers into plant cells.
- Chloroplast cells are specifically designed to carry out photolysis processes in response to light wave energy. Chlorophyll, a pigment material contained inside chloroplasts, absorbs this energy by transferring it to one of the electrons that make up its molecular structure. This electron breaks free from the chlorophyll and combines with a water molecule. When this happens, the water molecule splits into its hydrogen and oxygen components. These chemical reactions make up the light-dependent reactions within the photosynthesis process. The hydrogen atoms produced become energy carriers throughout the remainder of the photosynthesis process.
- Photolysis reactions take place in what are called photosystems contained inside plant chloroplast cells. Johnson County Community College explains that photosystems contain pigment and protein materials that work together to move light energy through the photolysis process. Light absorption happens inside antenna molecules designed to pick up light waves that fall within the blue, green and yellow wavelengths. These different wavelengths represent different energy frequencies within the electromagnetic spectrum. Absorbed energy is then transferred into reaction centers where the actual electron transfers take place.
- Photolysis light reactions take place inside two separate photosystems, called systems II and I. Photosystem II receives energy wavelengths within the 680 nanometer range, while photosystem I receives those that fall within the 700 nanometer range. Specialized molecules called P680 and P700 receive and transfer electron particles within the reaction center portions of these photosystems. These electron particles are then used to split water molecules into hydrogen and oxygen. From there, hydrogen molecules carry the energy captured by P680 and P700 through the remainder of the photosynthesis process.