Photosynthesis algae, photosynthesis takes place in organelles called chloroplasts. A typical plant cell contains about 10 to 100 chloroplasts. The chloroplast is enclosed by a membrane. This membrane is composed of a phospholipid inner membrane, a phospholipid outer membrane, and an intermembrane space. Enclosed by the membrane is an aqueous fluid called the stroma. Embedded within the stroma are stacks of thylakoids (grana), which are the site of photosynthesis. The thylakoids appear as flattened disks. The thylakoid itself is enclosed by the thylakoid membrane, and within the enclosed volume is a lumen or thylakoid space. Embedded in the thylakoid membrane are
Fractionation of carbon isotopes in oxygenic photosynthesis activity, and variations in cell growth and geometry. The isotopic fractionations of different photosynthetic pathways are uniquely characterized by these factors, as described below. A C3 plant uses C3 carbon fixation, one of the three metabolic photosynthesis pathways which also include C4 and CAM (described below). These plants are called "C3" due to the three-carbon compound (3-Phosphoglyceric acid, or 3-PGA) produced by the CO fixation mechanism in these plants. This C3 mechanism is the first step of the Calvin-Benson cycle, which converts CO and RuBP into 3-PGA. C3 plants are the most common type of plant, and typically thrive under