•of •H+ through a
•cotransporter.
•共同運輸蛋白
•(b) Cotransport of anions (陰離子的共同運輸)
•Figure 36.4b
维管植物的运输
• The “coattail” effect of cotransport (共同運輸)
– Is also responsible for the uptake of the sugar sucrose (neutral solute) by plant cells
• Vascular tissue transports nutrients throughout a plant; such transport may occur over long distances (長途運輸)
•Figure 36.1
维管植物的运输
Key Concepts
• Concept 36.1: Physical forces drive the transport of materials in plants over a range of distances
•(木質液)
•CO2
••1 Roots absorb water •and dissolved minerals •from the soil.
•H2O •Minerals
•O2 •Sugar
••5 Sugars are produced by •photosynthesis in the leaves.
– A transport protein (cotransporter) couples the passage of one solute to the passage of another
•細胞質 •H+
•低濃度H+ •高濃度NO3-
•H+ •H+
•–
•+
•H+
•–
•+
•–
•+ •H+
•H+
•cotransporter
•H+ •H+
•– •– •H+ •–
•+
•+ •H+
•+
•H+
•H+
•細胞外液
•高濃度H+ •低濃度NO3-
•Cell accumulates •anions (•NO3– , for •example) by •coupling their transport to the inward diffusion
•H+
•+ •H+
•Proton pump generates
•H+
•Proton pump
•H+
•membrane potential •and H+ gradient.
•H+ •Figure 36.3
•–
•+ •H+
•–
•H+ •+
维管植物的运输
• 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
• Transport 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)
维管植物的运输
The Central Role of Proton Pumps (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 can be harnessed (=used) to do work (作功)
– To drive the transport of many different solutes
•細胞質•CYTOPLASM •–
•+
•EXTRACELLULAR FLUID •細胞外液
•K+ •K+
•K+ •K+
•K+
•–
•+
•–
•+
•K+
•transporter
•K+
•–
•+
•Cations ( •K+ , for •example) are driven into the cell by the membrane potential.
• Specific transport proteins/transportor (專一性 輸送蛋白)
– Enable plant cells to maintain an internal environment different from their surroundings
• Solutes in cell: cation (陽離子), anion (陰離子), neutral solute (中性溶質)
low osmotic pressure=low [solute]=high [water]
high osmotic pressure=high [solute]=low [water]
• Direction of moving water
low osmotic pressure=low [solute]=high [water]
•！？
•！？
•！？
•報告完畢 •敬請指教
•！？
•！？
维管植物的运输
Effects of Differences in Water Potential 水勢差的效應
• To survive plants must balance water uptake and loss
• Differences in water potential drive water transport in plant cells (水勢差驅動植物細胞中的 水份運輸)
– Contribute to a voltage known as a membrane potential (膜電位), also a kind of potential energy
•細胞質•CYTOPLASM
•EXTRACELLULAR FLUID •細胞外液
•–
•+
•ATP
•–
•–
•+ •H+
The CO2 provides carbon for
•photosynthesis. Some O2
produced by photosynthesis is used in cellular respiration.
•H2O
•(蒸散作用)
•3 •Transpiration, the loss of water •from leaves (mostly through
• Concept 36.5: Organic nutrients are translocated through the phloem (韌皮部)
维管植物的运输
• Concept 36.1: Physical forces drive the transport of materials in plants over a range of distances
•高濃度H+
••H+ down the •低濃度sugar
•–
•+ •H+
•–
•+
•steep proton •gradient.
•H+
•S
•H+
•+ •–
•(c) Cotransport of a neutral solute (中性溶質的共同運輸)
•Figure 36.4c
维管植物的运输
•！？
维管植物的运输
Selective Permeability of Membranes: A Review 膜的選擇通透性----各種膜系統
• The selective permeability (選擇通透性) of a plant cell’s plasma membrane (細胞膜)
– Controls the movement of solutes into and out of the cell
维管植物的运输
• A variety of physical processes (物理過程) are involved in the different types of transport (眾 多物理過程介入或參與不同型式的運輸)
••4 Through stomata, leaves
take in CO2 and expel O2.
•–
•+ •Transport protein
•(transportor)
•(a) Membrane potential and cation uptake (陽離子的吸收)
•Figure 36.4a
维管植物的运输
• In the mechanism called cotransport (共同運輸)
•細胞質