Chapter 20. The Calvin Cycle and the Pentose Phosphate Pathway Flashcards
An enzyme that cleaves an aldol. Aldolases are important in carbohydrate metabolism.
Aldolase
in plants, a cyclic metabolic pathway in which carbon dioxide is incorporated into ribulose 1,5-bisphosphate to give compounds that can be used for the synthesis of glucose.
Calvin cycle (dark reactions)
The mixture of fructose 6-phosphate, glucose 1-phosphate and glucose 6-phosphate present in cells.
Hexose monophosphate pool
the transport of carbon dioxide in four-carbon compounds from mesophyll cells to bundle-sheath cells, where carbon fixation occurs; the pathway is found in tropical plants and is designed to prevent photorespiration at high environmental temperatures.
C 4 pathway
photosynthetic organisms that synthesize glucose from carbon dioxide and water, using sunlight as an energy source. The glucose is then used as a fuel for cellular metabolism.
Autotroph
organisms that obtain energy from chemical fuels only, and which are ultimately dependent on autotrophs for fuel.
Heterotroph
plants which lack the C4 pathway.
C 3 plant
small membrane-bound organelles that are present in most eukaryotes and play a role in detoxification, synthesis of plasmalogens and bile salts, and beta-oxidation of long-chain fatty acids.
Peroxisome (microbody)
the enzyme that catalyzes the reaction of carbon dioxide with ribulose 1,5-bisphosphate to form two molecules of 3-phosphoglycerate.
Rubisco (ribulose 1,5-biphosphate carboxylase/oxygenase)
The conversion of organic carbon into carbon dioxide without the production of energy-rich metabolites; the result of the oxygenase reaction catalyzed by rubisco and the subsequent regeneration of glucose from two molecules of glycolate, with the release of carbon dioxide and ammonia and the consumption of ATP.
Photorespiration
a plant that utilizes the C4 pathway.
C 4 plant
the enzyme that initiates the oxidative phase of the pentose phosphate pathway by oxidizing glucose 6-phosphate to 6-phosphoglucono-delta-lactone to generate one molecule of NADPH.
Glucose 6-phosphate dehydrogenase
a metabolic pathway that generates NADPH and five-carbon sugars such as ribose 5-phosphate from glucose 6-phosphate; also referred to as the hexose monophosphate shunt and the phosphogluconate pathway. It includes oxidative reactions which produce NADPH and ribose 5-phosphates as well as nonoxidative reactions which together convert five-carbon sugar phosphates to gluconeogenic precursors of glucose 6-phosphate.
Pentose phosphate pathway
an adaptation by plants living in arid environment. The C4 pathway concentrates carbon dioxide at night, and vapor exchange with the environment is curtailed during the heat of the day by closure of the stomata.
Crassulacean acid metabolism (CAM)
this tripeptide plays a role in combating oxidative stress by maintaining the reduced state of the cell. Glutathione cycles between the reduced (GSH) and oxidized state (GSSG).
Glutathione
