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26 terms

Photosynthesis

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light reactions
phase of photosynthesis where light energy is converted to chemical energy in the form of ATP and NADPH; results in the splitting of water and the release of oxygen; takes place in the thylakoid membranes
Calvin Cycle
Organic compounds (sugars) are formed using CO2 and the chemical energy stored in ATP and NADPH; takes place in the stroma
electromagnetic energy
A form of energy that travels through space as waves
visible light
That portion of the electromagnetic spectrum detected as various colors by the human eye, ranging in wavelength from about 380 nm to about 750 nm.
chlorophyll
principal pigment of plants and other photosynthetic organisms; captures light energy
accessory pigments
Pigments that absorbs light at wavelengths that are different from chlorophyll and then pass energy onto chlorophyll
autotroph
organism that can capture energy from sunlight or chemicals and use it to produce its own food from inorganic compounds; also called a producer
photoautotroph
An organism that harnesses light energy to drive the synthesis of organic compounds from carbon dioxide.
chloroplast
organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy
thylakoid
flattened sac within a Granum whose membrane contains chlorophyll; where the light reactions of photosynthesis occur
granum
a stack of thylakoids in a chloroplast
lumen
the space in the middle of thylakoid
stroma
The fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide.
electron transport chain
a series of molecules, found in the inner membranes of mitochondria and chloroplasts, through which electrons pass in a process that causes protons to build up on one side of the membrane
chemiosmosis
in chloroplasts and mitochondria, a process in which the movement of protons down their concentration gradient across a membrane through ATP synthase which results in the synthesis of ATP
NADPH
electron carrier that provides high-energy electrons for photosynthesis
CAM plant
A plant that uses crassulacean acid metabolism, an adaptation for photosynthesis in arid conditions, first discovered in the family Crassulaceae. Carbon dioxide entering open stomata during the night is converted into organic acids, which release CO2 for the Calvin cycle during the day, when stomata are closed.
C4 plant
A plant that prefaces the Calvin cycle with reactions that incorporate CO2 into a four-carbon compound, the end product of which supplies CO2 for the Calvin cycle.
C3 plant
A plant that uses the Calvin cycle for the initial steps that incorporate CO2 into organic material, forming a three-carbon compound as the first stable intermediate. (normal photosynthesis)
carbon fixation
The incorporation of carbon from carbon dioxide into an organic compound by an autotrophic organism.
photon
a tiny particle or packet of light energy
wavelength
The distance between crests of waves, such as those of the electromagnetic spectrum.
photosystem
A light-capturing unit located in the thylakoid membrane of the chloroplast or in the membrane of some prokaryotes, consisting of a reaction-center complex surrounded by numerous light-harvesting complexes.
reaction center
The chlorophyll a molecule and the primary electron acceptor in a photosystem; they trigger the light reactions of photosynthesis. The chlorophyll donates an electron, excited by light energy, to the primary electron acceptor, which passes an electron to an electron transport chain.
photophosphorylation
The process of generating ATP from ADP and phosphate by means of a proton-motive force generated by the thylakoid membrane of the chloroplast during the light reactions of photosynthesis.
photorespiration
A metabolic pathway that consumes oxygen and ATP, releases carbon dioxide, and decreases photosynthetic output. Photorespiration generally occurs on hot, dry, bright days, when stomata close and the oxygen concentration in the leaf exceeds that of carbon dioxide.