Enzyme that is part of an ATP synthase complex and functions in the production of ATP in chloroplasts and mitochondria.
C3 plant
Plant that fixes carbon dioxide via the Calvin cycle; the first stable product of C3 photosynthesis is a 3-carbon compound.
C4 plant
Plant that fixes carbon dioxide to produce a C4 molecule that releases carbon dioxide to the Calvin cycle.
Calvin cycle reaction
Portion of photosynthesis that takes place in the stroma of chloroplasts and can occur in the dark; it uses the products of the light reactions to reduce CO2 to a carbohydrate.
CAM
Crassulacean-acid metabolism; plant fixes carbon dioxide at night to produce a C4 molecule that releases carbon dioxide to the Calvin cycle during the day.
carbon dioxide (CO2) fixation
Photosynthetic reaction in which carbon dioxide is attached to an organic compound.
carotenoid
Yellow or orange pigment that serves as an accessory to chlorophyll in photosynthesis.
chlorophyll
Green pigment that absorbs solar energy and is important in algal and plant photosynthesis; occurs as chlorophyll a and chlorophyll b.
chloroplast
Membrane-bounded organelle in algae and plants with chlorophyll-containing membranous thylakoids; where photosynthesis takes place.
coenzyme
Nonprotein organic molecule that aids the action of the enzyme to which it is loosely bound.
electron transport chain
Passage of electrons along a series of electron carriers from a higher to lower energy level; the energy released is used for the synthesis of ATP.
grana
(sing., granum) Stack of chlorophyll-containing thylakoids in a chloroplast.
light reaction
Portion of photosynthesis that captures solar energy and takes place in thylakoid membranes of chloroplasts; it produces ATP and NADPH.
oxidation
Loss of one or more electrons from an atom or molecule; in biological systems, generally the loss of hydrogen atoms.
photosynthesis
Process occurring usually within chloroplasts whereby chlorophyll-containing organelles trap solar energy to reduce carbon dioxide to carbohydrate.
photosystem
Photosynthetic unit where solar energy is absorbed and high-energy electrons are generated; contains a pigment complex and an electron acceptor; occurs as PS (photosystem) I and PS II.
redox reaction
Oxidation-reduction reaction; one molecule loses electrons (oxidation) while another molecule simultaneously gains electrons (reduction).
reduction
Gain of electrons by an atom or molecule with a concurrent storage of energy; in biological systems, the electrons are accompanied by hydrogen ions.
RuBP carboxylase (rubisco)
Enzyme that is required for carbon dioxide fixation (atmospheric CO2 attaches to RuBP) in the Calvin cycle.
stomata (sing., stoma)
Small opening between two guard cells on the underside of leaf epidermis through which gases pass.
stroma
Fluid within a chloroplast that contains enzymes involved in the synthesis of carbohydrates during photosynthesis.
thylakoid
Flattened sac within a granum whose membrane contains chlorophyll and where the light reactions of photosynthesis occur.