植物生理学双语课件4

Chapter 4 Respiration in plant •Disscussion:•1.Does plant has special respiration pathway? 3030721001段颖慧, 3040709043刘旖璇, 3040709045,陈秀珍•2.What are similarity and difference between dark respiration and photorespiration? 3040709037姚雷钧, 3040709038马宇光, 3040912018于喆•3. What are similarity and difference between oxidative phosphorylation and photosynthetic phosphorylation? •3043023057袁迟, 3043023063段丽娜, 3043023087郗旺, 3040709067林明志•Section1. The concept and physiological role of respiration in plant• 1.1Concept of respiration• 1.1.1Aerobic respiration In the presence of molecular oxygen (O2), living cell makes respiratory substrates degrade (oxidize) thoroughly, companied with release of CO2 , formation of H2O and unlocking of energy.•Respiration substrates：sugar、fat or protein.•Normal substrate is glucose (G, C6H12O6)。

•C6H12O6+6O2→6CO2+6H2O+Energy(△G')•△G'=2870kJ(686kCal)/molFig 4-1The integration of aerobic respiration in plant including glycolysis, citric acid cycle (Tricarboxylic acid cycle ,TCA) , respiratory electron transfer and oxidative phosphorylation.1.1.2Anaerobic respirationIn the absence of O2, living cell makes respiratory substrates degrade partly, companied with unlocking of less energy.Fermentation in microbes.C6H12O6→2C2H5OH+2CO2+Energy△G`=100kJ/molC6H12O6→2CH3CHOHCOOH+Energy△G`=100kJ/molAdaptation to flooding and anaerobic condition.• 1.2 Physiological role of respiration•(1)Provide the energy for life activity,36-38ATP.•(2)Provide the intermediate products (skeleton) for other biosynthesis, keto acid (酮酸)and NAD(P)H。

•Glucose as an example, EMP pathway can be summed up as following reaction equation:•C6H12O6+2NAD+2ADP+2Pi→2CH3COCOOH +2NADH2+2ATP+2H2O•Key mediates：Pyr→Ala•PEP→OAA•PEP+E4P→C7……shikimic acid pathway(莽草酸途径)……aromatic amino acid (芳香族氨基酸) and plant hormones。

2.2、TCA cycle (Tricarboxylic acid cycle)TCA cycle is a program carried out inmitochondrial matrix under available O2, inwhich pyruvate is , step by step, degraded byoxidation into H2O and CO2--------------------Krebs cycle.•Sum of TCA cycle•In mitochondrial matrix.•Decarboxylation of 3 CO 2.•Removing 5 couple of hydrogen (4NADH 2, 1FADH 2 ).•Total equation:•2Pyr+8NAD +2FAD+2ADP+2Pi +4H 2O •→6 CO 2+2ATP+8NADH 2+2FADH 2•Key mediate products:•α-KG →Glu, Chl ，OAA →Asp , CH 3CO-CoA →Fatty acid ，NADH 2for other reduction or synthesis2.2Pentose phosphate pathway（PPP, HMP）•PPP is a process in which G6P is directly decarboxylated and dehydrogenated, and CO2 releases in the cytosol.•2 steps•Step1.6 G6P is dehydrogenated two times and decarboxylated one time, and forms 6 Ru5P.•Step2.6 Ru5P are recombined into 5 G6P.Role：1.Producing reduction power (NADPH2 ),2.Providing mediate products,R-5-P→dR5P……nuclear acid.E4P+ PEP→C7……shikimic acid pathway ……aromatic amino acid, plant hormones,phenols、quinones.3.Producing ATP,too?•PPP↑,upon flowering, oil seed developing, infection of plant diseases or insect.•Judging form：initial ratio, C6/ C1;if onlyPPP, the C6/ C1is 0；if only EMP-TCA, C6/C1is 1。

If the ratio is >0<1，both happen。

Section3. Biological oxidation •Biological oxidation——intensive definition: The process in living cell, under normal temperature and pressure, catalyzed by enzyme and releasing stored energy step by step, includes organic substrate degradation by oxygenation, O2 consumption, CO2and H2O production and release of stored energy to form ATP.•Special definition: respiratory electron transport and oxidative phosphorylation and O2uptake and H2O formation.2.1Structure and function of mitochondriabar ball shape: 1～2μm ×0.5～1.0 μm, 500～2000/cell。

Fig 4-4 Mitochondrial structure3.1Structure and function of mitochondriaFig 4-5 Mitochondrial structure shows respiratory chain3.2 Respiratory chainFig 4-6Complaxes of respiratory chain in mitochondrial cristaeFig 4-7Structure of alternate oxidase• 3.4 Oxidative phosphorylationA process in which ATP is synthesized with ADP and Pi, while the respiratory electron is transferred along respiratory chain to O.2•Mechanism：Mitchell’s chemical osmotic theory.•P/O is referred to number of ATP formation, while each one of atom of oxygen is consumed during respiration.•NADH2……→P/O=3（or 2）•FADH2……→P/O=2ATP formationSection 4 Regulation and organic substance synthesis associated with respiration• 4.1 Regulation of respiration• 4.1.1 Energy charge (EC) regulation: Adenyl acid levels regulate the respiratory metabolism.•EC reflects the energy levels in cell, and the following formula is often represented:•[ATP]+1/2[ADP]•EC= ——————————•[ATP]+[ADP]+[AMP]Section 5. Respiratory indexes and factors affecting respiration•5.1 Respiratory index5.1.1 Respiratory rate:•The quantity of release of CO2 (or uptake of O2 ) per unit weight (FW, DW, protoplast weight) per time (O2μmol/gDW.h, O2μmol /gFW.h).•Depends on species, ages, organs or tissues.• 5.1.2Respiratory Quotient(R.Q.)•or Respiratory coefficient:•Referred as the ratio of moles (or volumes) of released CO2to absorbed O2 by plant tissue at the same time.••moles (or volumes) of released CO2•R.Q.＝———————————————•moles (or volumes) of absorbed O2•Sugar as a substrate: R.Q.=1，•C6H12O6+6 O2→6CO2+6H2O•RQ=6molCO2/6mol O2=1.0•Sugar as a substrate: R.Q.=1，•C6H12O6+6 O2→6CO2+6H2O•RQ=6molCO2/6mol O2=1.0•Fatty acid as a substrate: RQ<1，•C6H12O2+8 O2=6CO2+6H2O•RQ=6/8=0.75•Sugar as a substrate: R.Q.=1，•C6H12O6+6 O2→6CO2+6H2O•RQ=6molCO2/6mol O2=1.0•Fatty acid as a substrate: RQ<1，•C6H12O2+8 O2=6CO2+6H2O•RQ=6/8=0.75•Organic acid as a substrate: RQ>1,•2C6H8O7+9O2→12CO2+8H2O•RQ.=12/9=4/3=1.33•R.Q. also depends on environmental O2，orother metabolism•.•Anaerobic respiration,------RQ>1•Conversion of fat acid to sugar----RQ<1，Conversion of sugar to fat acid ----RQ>1.。