BIOL 334 Lecture Notes - Lecture 26: Light-Independent Reactions, Malic Acid, Invertase

• School: Queen's University
• Department: Biology
• Course: BIOL 334
• Professor: William Charles Plaxton

Document Summary

Plant glycolysis exists in the cytosol and plastid. Cytosolic glycolytic enzymes are isozymes of their plastid counterparts encoded by distinct nuclear genes. U(cid:374)like a(cid:374)i(cid:373)als, pla(cid:374)t (cid:373)ito(cid:272)ho(cid:374)dria do(cid:374)=(cid:859)t respire fatty a(cid:272)ids, so glycolysis is usually the only way to fuel plant respiration. Plant cytosolic glycolysis plays similar roles as in animals: anaerobic energy (atp) production, providing mitochondria with respiratory substrates (e. g. pyruvate, production of anabolic precursors. Plant cytosolic glycolysis is a network of alternative reactions that provides increased metabolic flexibility: this helps plants to survive unavoidable abiotic (environmental) stresses; e. g. , anoxia, cold temps, salinity stress or drought, pi starvation, etc. There are 3 alter(cid:374)ate e(cid:374)zy(cid:373)e gly(cid:272)olyti(cid:272) (cid:858)(cid:271)ypasses(cid:859) whi(cid:272)h use ppi in place of atp: sucrose synthase, ppi-pfk, ppdk. The net atp yield of cytosolic plant glycolysis (1 sucrose 4 pyruvates): with invertase and atp-pfk: 4 atp per sucrose, with sucrose synthase, ppi-pfk, and ppdk: 12 atp per sucrose.