维管植物的运输

1、Copyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsPowerPoint Lectures for Biology, Seventh EditionNeil Campbell and Jane ReeceLectures by Chris RomeroChapter 36Transport in Vascular Plants維管植物的運輸維管植物的運輸Copyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsOverview

2、: Pathways for Survival of vascular plant (維維管植物存活途徑管植物存活途徑)For vascular plants, the evolutionary journey (演化之旅) onto land involved the differentiation of the plant body into roots and shoots (植物體分化為根與枝條)Vascular tissue transports nutrients throughout a plant; such transport may occur over long dist

3、ances (長途運輸)Figure 36.1Copyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsKey Concepts Concept 36.1: Physical forces drive the transport of materials in plants over a range of distances Concept 36.2: Roots absorb water and minerals from the soil Concept 36.3: Water and minerals as

4、cend from roots to shoots through xylem (木質部) Concept 36.4: Stomata help regulate the rate of transpiration (蒸散作用) Concept 36.5: Organic nutrients are translocated through the phloem (韌皮部)Copyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsConcept 36.1: Physical forces drive the tr

5、ansport of materials in plants over a range of distancesTransport in vascular plants occurs on three scales (三種尺度/三種層次)Transport of water and solutes by individual cells, such as root hairs (個別細胞水與溶質的運輸)Short-distance transport of substances from cell to cell at the levels of tissues and organs (組織與

6、器官內細胞間物質的短距離運輸)Long-distance transport within xylem and phloem at the level of the whole plant (整株植物木質部與韌皮部的長距離運輸)Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings A variety of physical processes (物理過程物理過程) are involved in the different types of transport (眾眾 多物理過程介入或參與不同型式的運輸多物

7、理過程介入或參與不同型式的運輸)Figure 36.2MineralsH2OCO2O2CO2O2H2OSugarLight Sugars are produced byphotosynthesis in the leaves.5 Sugars are transported asphloem sap to roots and otherparts of the plant.6 Through stomata, leaves take in CO2 and expel O2. The CO2 provides carbon forphotosynthesis. Some O2 produced

8、by photosynthesis is used in cellular respiration.4Transpiration, the loss of waterfrom leaves (mostly throughstomata), creates a force withinleaves that pulls xylem sap upward.3 Water and minerals aretransported upward fromroots to shoots as xylem sap.2 Roots absorb waterand dissolved mineralsfrom

9、the soil.1 Roots exchange gases with the air spaces of soil, taking in O2 and discharging CO2. In cellular respiration, O2 supports the breakdown of sugars.7(木質液木質液)(木質液木質液)(蒸散作用蒸散作用)(韌皮液韌皮液)Copyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsSelective Permeability of Membranes: A

10、Review膜的選擇通透性膜的選擇通透性-各種膜系統各種膜系統 The selective permeability (選擇通透性) of a plant cells plasma membrane (細胞膜) Controls the movement of solutes into and out of the cell Specific transport proteins/transportor (專一性輸送蛋白) Enable plant cells to maintain an internal environment different from their surroundin

11、gs Solutes in cell: cation (陽離子), anion (陰離子), neutral solute (中性溶質)Copyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsThe Central Role of Proton Pumps (質子唧筒質子唧筒) Proton pumps (質子唧筒) in plant cells Create a hydrogen ion gradient (氫離子梯度) that is a form of potential energy (潛能) that

12、 can be harnessed (=used) to do work (作功) Contribute to a voltage known as a membrane potential (膜電位), also a kind of potential energyFigure 36.3CYTOPLASMEXTRACELLULAR FLUIDATPH+H+H+H+H+H+H+H+Proton pump generates membrane potentialand H+ gradient.+Proton pump細胞質細胞質細胞外液細胞外液Copyright 2005 Pearson Edu

13、cation, Inc. publishing as Benjamin Cummings Plant cells use energy stored in the proton gradient (氫離子梯度) and membrane potential (膜電位), both of which are potential energy To drive the transport of many different solutesFigure 36.4a+CYTOPLASMEXTRACELLULAR FLUIDCations ( , for example) are driven into

14、 the cell by themembrane potential.Transport protein(transportor)K+K+K+K+K+K+K+K+(a) Membrane potential and cation uptake (陽離子的吸收陽離子的吸收)+transporter細胞質細胞質細胞外液細胞外液Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings In the mechanism called cotransport (共同運輸) A transport protein (cot

15、ransporter) couples the passage of one solute to the passage of anotherFigure 36.4bH+H+H+H+H+H+H+H+H+H+H+H+NO3 NO3 NO3 NO3 NO3 NO3 +NO3(b) Cotransport of anions (陰離子的共同運輸陰離子的共同運輸)H+of through acotransporter.Cell accumulates anions ( , for example) by coupling their transport to theinward diffusion 共

16、同運輸蛋白共同運輸蛋白高濃度高濃度H+低濃度低濃度NO3-低濃度低濃度H+高濃度高濃度NO3-cotransporter細胞質細胞質細胞外液細胞外液Copyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsFigure 36.4c The “coattail” effect of cotransport (共同運輸) Is also responsible for the uptake of the sugar sucrose (neutral solute) by plant cellsH+H+H+H+H+H+

17、H+H+H+H+SSSSSPlant cells canalso accumulate a neutral solute,such as sucrose( ), bycotransporting down thesteep protongradient.SH+H+H+S+(c) Cotransport of a neutral solute (中性溶質的中性溶質的共同運輸)cotransporter細胞外液細胞外液細胞質細胞質低濃度低濃度H+高濃度高濃度sugar高濃度高濃度H+低濃度低濃度sugarCopyright 2005 Pearson Education, Inc. publishi

18、ng as Benjamin Cummings報告完畢報告完畢敬請指教敬請指教！？！？！？！？！？！？！？！？！？！？！？！？Copyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsEffects of Differences in Water Potential水勢差的效應水勢差的效應 To survive plants must balance water uptake and loss Differences in water potential drive water transport in plan

19、t cells (水勢差驅動植物細胞中的水份運輸) Osmosis (滲透作用) Determines the net uptake or water loss by a cell Is affected by solute concentration and pressureCopyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Osmotic pressure (滲透壓) in animal cellslow osmotic pressure=low solute=high waterhigh osmot

20、ic pressure=high solute=low water Direction of moving water low osmotic pressure=low solute=high waterhigh osmotic pressure=high solute=low water Isotonic solution(等張溶液)、 hypertonic solution(高張溶液)、 hypotonic solution(低張溶液)watersolutewaterCopyright 2005 Pearson Education, Inc. publishing as Benjamin

21、Cummings Water potential (水勢) Is a measurement that combines the effects of solute concentration and pressure Determines the direction of movement of water Water Flows from regions of high water potential to regions of low water potential Solute (溶質溶質)WaterSoluteInOutMembraneCopyright 2005 Pearson E

22、ducation, Inc. publishing as Benjamin CummingsHow Solutes and Pressure Affect Water Potential Both pressure and solute concentration Affect water potential The solute potential of a solution Is proportional to the number of dissolved molecules Pressure potential Is the physical pressure on a solutio

23、nCopyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsQuantitative Analysis of Water Potential (水勢水勢) The addition of solutes reduces water potentialFigure 36.5a0.1 MsolutionH2OPurewater P = 0 S = 0.23 = 0.23 MPa = 0 MPa(a)High solute=Low water potentialLow solute=High water potenti

24、alCopyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Application of physical pressure (物理性壓力) Increases water potential (水勢)H2O P = 0.23 S = 0.23 = 0 MPa = 0 MPa(b)H2O P = 0.30 S = 0.23 = 0.07 MPa = 0 MPa(c)Figure 36.5b, cCopyright 2005 Pearson Education, Inc. publishing as Benja

25、min Cummings Negative pressure (負壓) Decreases water potentialH2O P = 0 S = 0.23 = 0.23 MPa(d) P = 0.30 S = 0 = 0.30 MPaFigure 36.5dCopyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsWater potential (水勢)Affects uptake and loss of water by plant cellsIf a flaccid cell (鬆弛細胞鬆弛細胞) is

26、placed in an environment with a higher solute concentrationThe cell will lose water and become plasmolyzed (膜壁分離)Figure 36.6a0.4 M sucrose solution:Initial flaccid cell:Plasmolyzed cellat osmotic equilibriumwith its surroundingsP = 0S = 0.7P = 0S = 0.9P = 0S = 0.9 = 0.9 MPa = 0.7 MPa = 0.9 MPaCopyri

27、ght 2005 Pearson Education, Inc. publishing as Benjamin Cummings If the same flaccid cell is placed in a solution with a lower solute concentration The cell will gain water and become turgid (膨脹)Distilled water:Initial flaccid cell:Turgid cellat osmotic equilibriumwith its surroundings P = 0 S = 0.7

28、 P = 0 S = 0 P = 0.7 S = 0.7Figure 36.6b = 0.7 MPa = 0 MPa = 0 MPaCopyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Turgor (膨壓) loss in plants causes wilting (萎凋) Which can be reversed when the plant is watered (澆水)Figure 36.7Copyright 2005 Pearson Education, Inc. publishing as

29、Benjamin Cummings報告完畢報告完畢敬請指教敬請指教！？！？！？！？！？！？！？！？！？！？！？！？Copyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsAquaporin Proteins and Water Transport Aquaporins (水孔蛋白水孔蛋白) Are transport proteins (運轉蛋白) in the cell membrane that allow the passage of water Do not affect water potential

30、Copyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsThree Major Compartments (區間區間) of Vacuolated Plant Cells Transport is also regulated By the compartmental structure of plant cells Compartmentation (區間化/區隔化/間隔化) Cell wall (細胞壁) Cytosol (細胞質液) Vacuole (液胞)Copyright 2005 Pearson E

31、ducation, Inc. publishing as Benjamin Cummings The plasma membrane (細胞膜) Directly controls the traffic of molecules into and out of the protoplast Is a barrier between two major compartments (區間), the cell wall and the cytosolCopyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsCell

32、 compartments (細胞間隔細胞間隔) ：同一細胞內：同一細胞內The third major compartment in most mature plant cells is the vacuole, a large organelle that can occupy as much as 90% of more of the protoplasts volume The vacuolar membrane (液胞膜液胞膜) regulates transport between the cytosol and the vacuoleFigure 36.8aTransport p

33、roteins in the plasma membrane regulate traffic of molecules between the cytosol and the cell wall.Transport proteins inthe vacuolar membrane regulate traffic of molecules between the cytosol and the vacuole.3. Plasmodesma(細胞質連絡絲細胞質連絡絲)1. Vacuolar membrane(tonoplast) (液胞膜液胞膜)2. Plasma membraneCell w

34、allCytosolVacuoleCell compartments. The cell wall, cytosol, and vacuole are the three maincompartments of most mature plant cells.(a)Three compartmentsCopyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings In most plant tissuesThe cell walls and cytosol are continuous from cell to ce

35、ll The cytoplasmic continuumIs called the symplast (共質體/合胞體) The apoplast (離質體/非原質體/質外體)Is the continuum of cell walls plus extracellular spacesCopyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsTissue compartments (組織間隔組織間隔) ：不同細胞間：不同細胞間Figure 36.8bKeySymplastApoplastThe symplast

36、 is thecontinuum ofcytosol connectedby plasmodesmata.The apoplast isthe continuumof cell walls andextracellularspaces.Apoplast1. Transmembrane route2. Symplastic route3. Apoplastic routeSymplastTransport routes between cells. At the tissue level, there are three passages: the transmembrane, symplast

37、ic, and apoplastic routes. Substances may transfer from one route to another.(b)(共質體途徑共質體途徑)(質外體途徑質外體途徑)(質外體質外體)(共質體共質體)(穿越細胞膜途徑穿越細胞膜途徑)Copyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsFunctions of the Symplast and Apoplast in Transport Water and minerals can travel through a pl

38、ant by one of three routes Out of one cell, across a cell wall, and into another cell Via the symplast (共質體/合胞體) Along the apoplast (離質體/非原質體/質外體)Copyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsBulk Flow in Long-Distance Transport長距離運輸的巨流長距離運輸的巨流 In bulk flow (巨流) Movement of f

39、luid (sap) in the xylem and phloem is driven by pressure differences (壓力差) at opposite ends of the xylem vessels (木質部導管) and phloem sieve tubes (韌皮部篩管)Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings報告完畢報告完畢敬請指教敬請指教！？！？！？！？！？！？！？！？！？！？！？！？Copyright 2005 Pearson Education, Inc.

40、publishing as Benjamin Cummings Concept 36.2: Roots absorb water and minerals from the soil Water and mineral salts (礦物鹽) from the soil Enter the plant through the epidermis of roots and ultimately flow to the shoot systemCopyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsLateral

41、transport (側向運輸側向運輸) of minerals and water in rootsFigure 36.9卡氏帶卡氏帶維管束維管束導管導管(1) Uptake of soil solution by the hydrophilic walls of root hairs provides access to the apoplast. Water and minerals can then soak into the cortex along this matrix of walls.(2) Minerals and water that crossthe plasma me

42、mbranes of roothairs enter the symplast.(3) As soil solution moves alongthe apoplast, some water andminerals are transported intothe protoplasts of cells of theepidermis and cortex and thenmove inward via the symplast.(4) Within the transverse and radial walls of each endodermal cell is the Casparia

43、n strip, a belt of waxy material (purple band) that blocks the passage of water and dissolved minerals. Only minerals already in the symplast or entering that pathway by crossing the plasma membrane of an endodermal cell can detour around the Casparian strip and pass into the vascular cylinder.(5) E

44、ndodermal cells and also parenchyma cells within thevascular cylinder discharge water and minerals into theirwalls (apoplast). The xylem vessels transport the waterand minerals upward into the shoot system.Casparian stripPathway along apoplast Pathway throughsymplastPlasmamembraneApoplasticrouteSymp

45、lasticrouteRoot hairEpidermisCortexEndodermisVascular cylinderVessels(xylem)Casparian stripEndodermal cell卡氏帶卡氏帶(共質體途徑共質體途徑)(質外體途徑質外體途徑)(共質體共質體途徑途徑)(質外體途徑質外體途徑)345表皮表皮皮層皮層內皮內皮4512Copyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsThe Roles of Root Hairs, Mycorrhizae, and Cortical

46、Cells Much of the absorption of water and minerals occurs near root tips, where the epidermis is permeable to water and where root hairs are located Root hairs account for much of the surface area of rootsCopyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Most plants form mutuall

47、y beneficial relationships (互利共生) with fungi, which facilitate (促進) the absorption of water and minerals from the soil Roots and fungi form mycorrhizae (菌根), symbiotic structures(共生結構) consisting of plant roots united with fungal hyphae (菌絲)Figure 36.102.5 mm菌根菌根是真菌與根的共生結合是真菌與根的共生結合Copyright 2005 Pe

48、arson Education, Inc. publishing as Benjamin Cummings Once soil solution enters the roots The extensive surface area of cortical cell membranes enhances uptake of water and selected mineralsCopyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsThe Endodermis: A Selective Sentry (選擇性進

49、入選擇性進入) The endodermis (內皮層內皮層) Is the innermost layer (最內層) of cells in the root cortex Surrounds the vascular cylinder and functions as the last checkpoint (最後關卡) for the selective passage of minerals from the cortex (皮質) into the vascular tissue (維管束組織)Copyright 2005 Pearson Education, Inc. publi

50、shing as Benjamin Cummings Water can cross the cortex (皮層) Via the symplastic (共質體的) or apoplastic route (質外體的路徑) The waxy Casparian strip (卡氏帶) of the endodermal wall (內皮細胞壁) Blocks apoplastic transfer of minerals from the cortex to the vascular cylinderCopyright 2005 Pearson Education, Inc. publis

51、hing as Benjamin Cummings報告完畢報告完畢敬請指教敬請指教！？！？！？！？！？！？！？！？！？！？！？！？Copyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsConcept 36.3: Water and minerals ascend (升高) from roots to shoots through the xylemPlants lose an enormous amount of water through transpiration, the loss of water v

52、apor from leaves and other aerial parts of the plantThe transpired water must be replaced by water transported up from the rootsMineralsH2OCO2O2CO2O2H2OSugarLightCopyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsFactors Affecting the Ascent of Xylem SapXylem sap (木質部汁液) Rises to

53、heights of more than 100 m in the tallest plantsCopyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsPushing Xylem Sap: Root Pressure (根壓根壓) At night, when transpiration is very low Root cells continue pumping mineral ions into the xylem of the vascular cylinder, lowering the water

54、potential Water flows in from the root cortex (根的皮層) Generating root pressure (根壓) in the xylem Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings Root pressure (根壓) sometimes results in guttation (點泌作用), the exudation (滲出作用) of water droplets (小水滴) on tips of grass blades or the

55、 leaf margins (葉緣) of some small, herbaceous eudicots (草本的真雙子葉植物)Figure 36.11Copyright 2005 Pearson Education, Inc. publishing as Benjamin Cummings報告完畢報告完畢敬請指教敬請指教！？！？！？！？！？！？！？！？！？！？！？！？Copyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsPulling Xylem Sap: The Transpiration-Cohesi

56、on-Tension Mechanism (拉升木質液拉升木質液：蒸散作用內聚力蒸散作用內聚力-附著力附著力-張力的作用機制張力的作用機制) Water is pulled upward by negative pressure (負壓) in the xylemTranspirational Pull (蒸散作用的拉力蒸散作用的拉力) Water vapor in the airspaces of a leaf Diffuses down its water potential gradient and exits the leaf via stomataCopyright 2005 Pea

57、rson Education, Inc. publishing as Benjamin Cummings Transpiration produces negative pressure (tension) in the leaf which exerts a pulling force (拉力) on water in the xylem, pulling water into the leaf Evaporation causes the air-water interface to retreat farther into the cell wall and become more cu

58、rved as the rate of transpiration increases. As the interface becomes more curved, the water films pressure becomes more negative. This negative pressure, or tension, pulls water from the xylem, where the pressure is greater.CuticleUpper epidermisMesophyllLower epidermisCuticleWater vaporCO2O2XylemC

59、O2O2Water vaporStomaEvaporation At first, the water vapor lost bytranspiration is replaced by evaporation from the water film that coats mesophyll cells. In transpiration, water vapor (shown as blue dots) diffuses from the moist air spaces of the leaf to the drier air outside via stomata. AirspaceCy

60、toplasmCell wallVacuoleEvaporationWater filmLow rate oftranspirationHigh rate oftranspirationAir-water interfaceCell wallAirspaceY Y = 0.15 MPa Y Y = 10.00 MPa312Figure 36.12Air-spaceCopyright 2005 Pearson Education, Inc. publishing as Benjamin CummingsCohesion and Adhesion in the Ascent of Xylem Sa