The biochemistry of photosynthesis Flashcards
ligth dependent reactions
the reactions that take place in the light on the thylakoid membranes of the chloroplasts; the reactions produce ATP and break down water molecules in a photochemical reaction, providing hydrogen ions to reduce carbon dioxide and produce carbohydrates
light-independent reactions
the reactions that use the reduced NADP and ATP produced by the light-dependent stage of photosynthesis in a pathway known as the Calvin cycle; this occurs in the stroma of the chloroplast and results in the reduction of carbon dioxide from the air to cause the synthesis of carbohydrates
photochemical reaction
a reaction initiated by light
cyclic phosphorylation
a process that drives the production of ATP; light-excited electrons from PS1 are taken up by an electron acceptor and transferred directly along an electron transport chain to produce ATP, with the electron returning to PS1
non-cyclic phosphorylation
a process involving both PS1 and PS2 in which water molecules are broken into smaller units using light energy to provide reducing power to make carbohydrates and at the same time to produce ATP
photolysis
the breaking down of a molecule into smaller units using light
ribulose bisphosphate (RuBP)
a five-carbon compound that combines with carbon dioxide from the air in the Calvin cycle to fix carbon dioxide and form a six carbon compound
RUBISCO
a rate-controlling enzyme that catalyses the reaction between carbon dioxide/oxygen and ribulose bisphosphate
glycerate 3-phosphate (GP)
a 3-carbon compound thought to be the result of breakdown of a theoretical highly unstable 6-carbon compound formed as a result of the reaction between RuBP and carbon dioxide in the Calvin cycle
glyceraldehyde 3-phosphate
a 3-carbon sugar produced in the Calvin cycle using reduced NADP and ATP from the light-dependent-stage; GALP is the key product of photosynthesis and is used to replace the RuBP needed in the first step of the cycle, in glycolysis and the Krebs cycles, and in the synthesis of amino acids, lipids, etc. for the plant cells
photorespiration
the alternative reaction catalysed by RUBISCO in a low carbon dioxide environment which uses oxygen and releases carbon dioxide, making photosynthesis less efficient
glucogenesis
the synthesis of glucose from non-carbohydrates
limiting factors
the factors needed for a reaction to progress that is closest to its minimum value
