Plant cell anatomy. a Generalized drawing. b, Transmission electron micrograph of young leaf cell. See Table 4.1 for a description of these structures, along with a listing of their functions. microtubule uclear central vacuole nuc nucleolus nuclear chloroplas rough ER smooth ER plasma membrane Golgi apparatus mitochondrion intracellular space middle lamella cell wall of adjacent cell Figure 1-0
Figure 1-0
OUTSIDE OF CELL Water molecules Water-selective pore (aquaporin Membrane bilayer CYTOPLASM
⚫ Figure 1-1
aA thistle tube, covered at the broad end by .ter Osmosis demonstration less wate a10% sugar solution. The beaker contain略 solution rises due to movement 5% sugar solution. b. The solute(green of water toward net movement of water circles) is unable to pass through the to inside of thistle tube higher percentage membrane, but the water passes freely of solute through in both directions, A net movement of solute water toward the inside of the thistle tube occurs because the thistle tube has a higher percentage of solute. C In the end, the level of the solution rises in the thistle tube until more water hydrostatic pressure increases to the level of(lower osmotic pressure. percentage of solute) membrane a In the beginning b h the meantime c In the end Figure 1-2
Figure 1-2
(a)In hypotonic uole of a plant cell fills but the rigid cell walls prevent the cell from expanding. The ells of this healthy begonia plant are turgid. (b and c)When the begonia plant is exposed to a hypertonic solution, its cel become plasmolyzed as they lose water. The plant wilts and eventually dies. (Dennis Plasn Nucleus membrane Vacuole Vacuole membrane ( tonoplast Cytoplasm asma membrane Figure 1-2-1
Figure 1-2-1
Osmosis in Isotonic Hypertonic animal and plant cells. Hypotonic Conditions Conditions Conditions Animal a. No net movement of water b, Water enters the cell, whicl c. Water exits the cell, which into and out of the cell may burst(lysis)due to shrivels(crenation osmotic pressure Plant Cells sma membrane chloroplast d No net movement of water e. Vacuoles fill the water, turgor t. Vacuoles lose water. the Figure 1-2-2 into and out of the cell pressure develops, and cytosol shrinks(pla osmosiS chloroplasts are seen next to and chloroplasts are seen in the cell wall the center of the cell
Figure 1-2-2
(A) Pure water (8) solution conteining o 1 M sucrose 0.1 M sucrose solution Pure water "n=o MPa p- MP 0.244mPa O MPa a o MPa (C) Flaccid cell dropped into sucrose solution (D) Concentration of sucrose increased :2 cid coil Turgid cell Pp-0 488 MPa MPa -°232AM 0.3As Cell after equilbrium cell after equilibrium solution vw=-0.732MP Wn.O MPa w=-0.244MPa s=-0.732MP 0.732MP s=-0.732MPe vp=w-"=0.488MPa F'p-yw-s-0 MPa w=-0.732MPa (E) Pressure applied to cell Applied pressure squeezes v from -0.732 to-1464 Mpbling 0. 1 M sucrose solution Coll in nitial state Cell in final state 0.732MPa =-144MF v口="w-"=0.a8aMPa ="w-"=1.22MP FIGURE 3.9 Five examples illustrating the concept of water potential and its soell ponents.(A) Pure water.(B)A solution containing o I M Sucrose,(o)A flaccid c (in air) is clreppeet in the o1 M sucrose solution Because the starting water poten of the soluition, and the result is a cell with a positive turgor The ineihg the coneentration of sucrose in the solution maker the cell lose water all wall (i.e. the ofi mure. In this case and the cell wall. (B Another way to make the cell lose water is te press it slow ly F between two plates. In this case, half of the cell water is removedl, sea cell osmotic Igure 1-2-3 potential Incenses by a lctor ot 2
Figure 1-2-3
0.5 O -0.5 1.O 1.5 -2.5 O.9 1.2 1.3 1.4 Fig. 1-3 Relatio
Fig. 1-3
endode pericycle xylen epiderm root hair b. Vascular cylinder 50m Zone of xylem of rox cylinder Vascular strip water and Zone of minerals C. Endodermis Zone of Cell Division Dicot root tip. aection such Pas this. b. The vascular cylinder of a dicot root contains the vascular tissue. xylem is typically star shaped, and loom lies between the points of the star. c. Endodermis showing Figure 1-5-0 Becaume of the Casparian strip, water and minerals must pass through the cytoplasm of endodermal cells. in this way, endodermal colls requlate the passage of minerals into the vascular oylinder
Figure 1-5-0
Endodermis Casparian stri Symplastic and transmembrane pathways Pericycle Xylem Phloem Apoplast pathway FIGURE 4.3 Pathways for water uptake by the root Through the cortex, water may travel via the apoplast pathway, the transmembrane pathway, and the symplast pathway. In the symplast pathway, water flows between cells through the plasmod esmata without crossing the plasma membrane. In the transmembrane pathway. igure 1-5 F water moves across the plasma membranes, with a short visit to the cell wall space At the endodermis, the apoplast pathway is blocked by the Casparian strip
Figure 1-5
(A) 0 A Figure 17.23 ABA-induced stomatal closure. Epidermal strips of Commelina communis L incubated in buffer(10 mM Pipes pH 6.8)containing 50 mM KCl and supplied with CO-free air. The stomata are open wide after two to three hours(A). When transferred to the same solution plus 10 HM ABA, the pores close completely within 10 to 30 minutes(B) Figure 1-6-0
Figure 1-6-0
