BIOL 2061 1st Edition Lecture 14Outline of Last Lecture I. Plant nutrientsII. Water III. LightIV. Carbon dioxideV. SoilVI. NitrogenOutline of Current Lecture I. Plant cellular transportII. Cellular water contentIII. Tissue level transportIV. TranspirationV. Phloem transport/loading Current LectureI. Plant cellular transport-a. Passive transport- movement of materials into or out of cells down a concentration gradient without using ATPb. Passive diffusion- movement of a solute through a phospholipid bilayer down a gradient.c. Facilitated diffusion- transport of molecules across a plasma membrane down a concentration gradient with the help of a transport protein.i. Channels or transportersd. Osmosis- the movement of water across selectively permeable membranesi. Aquaporins allow facilitated diffusion of watere. Active transport- membrane transporter proteins use energy to move a substance against their concentration gradient.II. Cellular Water Content-These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.a. Water content of plant cells depends on osmosis which depends on solute concentration.i. Turgor pressure- hydrostatic that increases as water enters plant cellsb. Turgid= cytosol is full of water and the plasma membrane is pushing agains cell wallc. Plasmolyzed= has lost so much water that the turgor pressure is lostd. Flaccid= cell is between the 2 extremese. Water Potential-i. Potential energy of waterii. Measured in megapascals (MPa)iii. Used to:1. Understand the movement into and out of cells (cellular water potential)2. To understand water status of entire plant or organ (relative watercontent)III. Tissue Level Transport-a. Transmembrane Tansport- export of material from one cell to another cell with the help transporter proteinsb. Symplastic transport- movement of a substance from the cytosol of one cell to the cytosol of an adjacent cell with help of a plasmodesmata (tunnel)c. Apoplastic transport- movement of solutes along cell walls and spaces between cellsi. Apoplast- continuum of water-soaked cell walls and intercellular spaces. (around cells)IV. Transpiration-a. The evaporation of water from plant surfaces- through the stomatab. Sun’s energy indirectly powers transpirationc. Water is cohesive due to hydrogen bondingd. Stomatal movements-i. Guard cells close to conserve waterii. Blue light stimulates cell ion uptake, water flows in, cell expands and stomata opensiii. At night the ions pump out and the stomata closeiv. ABA can also close stomata during the daye. Leaf Abscission or leaf drop-i. Occurs normally to prevent water stressii. Allows plants to avoid embolism (clot)iii. Also reduces the amount of root mass that plants must produce to obtainwater in arid conditionsV. Phloem transport-a. Water flows where there are more solutesb. Sugar flow goes downc. Phloem loading-i. Symplastic-1. Does not require ATP2. Sugar does not have cross plasma membrane3. Woody plants transport sucrose form sugar- producing cells of the leaf to companion cells then to the sieve-tube elements via plasmodesmataii. Partly Apoplastic-1. Load sugar into sieve-tube elements of companion cells from intercellular spaces2. ATP must be used to move sugar across a plasma membrane into acompanion cells or sieve-tube