<P> Most organisms that utilize oxygenic photosynthesis use visible light for the light - dependent reactions, although at least three use shortwave infrared or, more specifically, far - red radiation . </P> <P> Some organisms employ even more radical variants of photosynthesis . Some archea use a simpler method that employs a pigment similar to those used for vision in animals . The bacteriorhodopsin changes its configuration in response to sunlight, acting as a proton pump . This produces a proton gradient more directly, which is then converted to chemical energy . The process does not involve carbon dioxide fixation and does not release oxygen, and seems to have evolved separately from the more common types of photosynthesis . </P> <P> In photosynthetic bacteria, the proteins that gather light for photosynthesis are embedded in cell membranes . In its simplest form, this involves the membrane surrounding the cell itself . However, the membrane may be tightly folded into cylindrical sheets called thylakoids, or bunched up into round vesicles called intracytoplasmic membranes . These structures can fill most of the interior of a cell, giving the membrane a very large surface area and therefore increasing the amount of light that the bacteria can absorb . </P> <P> In plants and 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 integral and peripheral membrane protein complexes of the photosynthetic system . </P>

Describe the general energy transfer that occurs in photosynthesis