•of •H+ throug輸蛋白
•(b) Cotransport of anions (陰離子的共同運輸)
•Figure 36.4b
• The “coattail” effect of cotransport (共同運輸)
– Is also responsible for the uptake of the sugar sucrose (neutral solute) by plant cells
•–
•+ •Transport protein
•(transportor)
•(a) Membrane potential and cation uptake (陽離子的吸收)
•Figure 36.4a
• In the mechanism called cotransport (共同運輸)
– A transport protein (cotransporter) couples the passage of one solute to the passage of another
•報告完畢 •敬請指教
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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)
维管植物的运输
2020年7月26日星期日
• Overview: Pathways for Survival of vascular plant (維 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)
•(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.
• 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
• Specific transport proteins/transportor (專一性 輸送蛋白)
• Concept 36.2: Roots absorb water and minerals from the soil
• Concept 36.3: Water and minerals ascend from roots to shoots through xylem (木質部)
• Concept 36.4: Stomata help regulate the rate of transpiration (蒸散作用)
•stomata), creates a force within
•leaves that pulls xylem sap
upward.
•(木質液)
•2• Water and minerals are •transported upward from •roots to shoots as xylem sap.
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
•water •solute
high osmotic pressure=high [solute]=low [water]
• Isotonic solution(等張溶液)、 hypertonic solution(高張溶液)、 hypotonic solution(低張溶液)
•taking in O2 and discharging •CO2. In cellular respiration, •O2 supports the breakdown •of sugars.
Selective Permeability of Membranes: A Review 膜的選擇通透性----各種膜系統
• Osmosis (滲透作用)
– Determines the net uptake or water loss by a cell
– Is affected by solute concentration and pressure
• Osmotic pressure (滲透壓) in animal cells
•H+
•+ •H+
•Proton pump generates
•H+
•Proton pump
•H+
•membrane potential •and H+ gradient.
•H+ •Figure 36.3
•–
•+ •H+
•–
•H+ •+
• 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 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.
•Light
•(韌皮液)
••6 Sugars are transported as •phloem sap to roots and other •parts of the plant.
•O2 •CO2
•Figure 36.2
••7 Roots exchange gases
•with the air spaces of soil,
– Short-distance transport of substances from cell to cell at the levels of tissues and organs (組織與器官內細胞 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)
• Vascular tissue transports nutrients throughout a plant; such transport may occur over long distances (長途運輸)
•Figure 36.1
Key Concepts
• 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
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•細胞質
•低濃度H+ •高濃度su•Sgar
•–
•H+ •–
•H+
•–
•+
•H+
•H+
•+
•+
•H+
•H+
•細胞外液
•Plant cells can •also accumulate a •neutral solute, •such as sucrose
•H+
•cotransporter •H–+
•H+ •( •S ), by •cotransporting
• Transport in vascular plants occurs on three scales (三種尺 度/三種層次)