Chloroplast
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Basic diagram of a chloroplast.
One of the most important organelles of a plant cell is the chloroplast. The chloroplast is the area in which photosynthesis takes place. They produce sugars for the plant to use. Check out the Mitochondrion page for more information about what happens to these sugars. The shape of a chloroplast is an oval shape. There are two membranes, an outer and an inner, with some space in between. Within the inner membrane, there are disk shaped structures called thylakoids, stacked in groups called grana (singular is granum). The rest of the space within the inner membrane is filled with a liquid called the stroma. All of the process of photosynthesis is held in the membranes of the thylakoids and in the stroma. There are structures called photosystems embedded into the membranes of thylakoids. There, the first part of photosynthesis takes place. Chlorophyll, a pigment that reflects green light, absorbs sunlight which sends electrons through an electron transport chain that pumps H+ ions from the stroma into the thylakoid. The electrons are then passed into empty NADP "buckets," making them NADPH+. The electrons are replenished by the splitting of water molecules, producing oxygen and H+ ions to add to the total inside the thylakoid. The oxygen atoms combine into O2, the oxygen that we breathe. The H+ ions are then passed through a structure called ATP synthase, which combines ADP and a phosphate group together into ATP. The NADPH+ and ATP are then sent into the stroma, where the Calvin Cycle takes place. The Calvin Cycle uses CO2 from the air, along with the NADPH+ and ATP to produce sugars as nutrients for the plant.