01/01/2011 · Illuminating Photosynthesis
Plants get carbon dioxide from the air through their leaves. The carbon dioxide diffuses through small holes in the underside of the leaf called stomata. (singular: stoma. plural: stomata)
The lower part of the leaf has loose-fitting cells, to allow carbon dioxide to reach the other cells in the leaf. This also allows the oxygen produced in photosynthesis to leave the leaf easily.
Carbon dioxide is present in the air we breathe, at very low concentrations. Even though it forms about .04% of the air, it is a needed factor in light-independent photosynthesis.
In higher concentrations, more carbon is incorporated into carbohydrate, therefore increasing the rate of photosynthesis in light-independent reactions.
This tutorial introduces photosynthesis
The plant uses the largest molecules to construct cell walls as the plant grows larger.The following equation sums up the photosynthesis reaction:
Sunlight + 6H2O + 6CO2 → C6H12O6 + 6O2In words, this equation states that sunlight, combined with six molecules of water (H2O) and six molecules of carbon dioxide (CO2), produces one molecule of sugar (C6H12O6) and six molecules of oxygen gas (O2).Through this process, green plants capture energy from the sun, use some of it to function and grow, and store some of it in their plant structure, where it’s available to other organisms when they eat the plants.
Photophosphorylation is the production of ATP using the energy of sunlight. Photophosphorylation is made possible as a result of chemiosmosis. Chemiosmosis is the movement of ions across a selectively permeable membrane, down their concentration gradient. During photosynthesis, light is absorbed by chlorophyll molecules. Electrons within these molecules are then raised to a higher energy state. These electrons then travel through Photosystem II, a chain of electron carriers and Photosystem I. As the electrons travel through the chain of electron carriers, they release energy. This energy is used to pump hydrogen ions across the thylakoid membrane and into the space within the thylakoid. A concentration gradient of hydrogen ions forms within this space. These then move back across the thylakoid membrane, down their concentration gradient through ATP synthase. ATP synthase uses the energy released from the movement of hydrogen ions down their concentration gradient to synthesise ATP from ADP and inorganic phosphate.