Bio 226: Cell and Molecular Biology - PowerPoint PPT Presentation

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Bio 226: Cell and Molecular Biology

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WATER Plants' most important chemical most often limits productivity – PowerPoint PPT presentation

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Title: Bio 226: Cell and Molecular Biology


1
  • WATER
  • Plants' most important chemical
  • most often limits productivity

2
  • WATER
  • Plants' most important chemical
  • most often limits productivity
  • Often gt90 of a plant cells weight

3
  • WATER
  • Plants' most important chemical
  • most often limits productivity
  • Often gt90 of a plant cells weight
  • Gives cells shape

4
  • WATER
  • Plants' most important chemical
  • most often limits productivity
  • Often gt90 of a plant cells weight
  • Gives cells shape
  • Dissolves many chem

5
  • WATER
  • Dissolves many chem
  • most biochem occurs in water
  • Source of e- for PS

6
  • WATER
  • most biochem occurs in water
  • Source of e- for PS
  • Constantly lose water due to PS (1000 H2O/CO2)

7
  • WATER
  • most biochem occurs in water
  • Source of e- for PS
  • Constantly lose water due to PS
  • Water transport is crucial!

8
  • WATER
  • Water transport is crucial!
  • SPAC Soil Plant Air Continuum
  • moves from soil-gtplant-gtair

9
WATER Formula H2O Formula weight 18
daltons Structure tetrahedron, bond angle
104.5
10
WATER Structure tetrahedron, bond angle
104.5 polar O is more attractive to electrons
than H ? on H ?- on O
11
Water Polarity is reason for waters properties
water forms H-bonds with polar molecules
12
Water Polarity is reason for waters properties
water forms H-bonds with polar
molecules Hydrophilic polar molecules Hydropho
bic non-polar molecules
13
  • Properties of water
  • Cohesion water H-bonded to water
  • -gt reason for surface tension

14
  • Properties of water
  • Cohesion water H-bonded to water
  • -gt reason for surface tension
  • -gt why water can be drawn from roots to leaves

15
Properties of water 1) Cohesion water H-bonded
to water 2) Adhesion water H-bonded to
something else
16
  • Properties of water
  • 1) Cohesion water H-bonded to water
  • 2) Adhesion water H-bonded to something else
  • Cohesion and adhesion are crucial for water
    movement in plants!

17
  • Properties of water
  • 1) Cohesion water H-bonded to water
  • 2) Adhesion water H-bonded to something else
  • Cohesion and adhesion are crucial for water
    movement in plants!
  • Surface tension adhesion in mesophyll creates
    force that draws water through the plant!

18
  • Properties of water
  • 1) Cohesion water H-bonded to water
  • 2) Adhesion water H-bonded to something else
  • 3) high specific heat
  • absorb heat when break H-bonds cools leaves

19
  • Properties of water
  • 1) Cohesion water H-bonded to water
  • 2) Adhesion water H-bonded to something else
  • 3) high specific heat
  • absorb heat when break H-bonds
  • Release heat when form H-bonds

20
Properties of water 1) Cohesion water H-bonded
to water 2) Adhesion water H-bonded to
something else 3) high specific heat 4) Ice floats
21
Properties of water 1) Cohesion water H-bonded
to water 2) Adhesion water H-bonded to
something else 3) high specific heat 4) Ice
floats 5) Universal solvent
22
  • Properties of water
  • 1) Cohesion water H-bonded to water
  • 2) Adhesion water H-bonded to something else
  • 3) high specific heat
  • 4) Ice floats
  • 5) Universal solvent
  • Take up transport
  • nutrients dissolved in
  • water

23
  • Properties of water
  • 5) Universal solvent
  • Take up transport nutrients dissolved in water
  • Transport organics dissolved in water

24
Properties of water 1) Cohesion water H-bonded
to water 2) Adhesion water H-bonded to
something else 3) high specific heat 4) Ice
floats 5) Universal solvent 6) Hydrophobic bonds
25
Properties of water 1) Cohesion water H-bonded
to water 2) Adhesion water H-bonded to
something else 3) high specific heat 4) Ice
floats 5) Universal solvent 6) Hydrophobic
bonds 7) Water ionizes
26
pH H acidity of a solution pH convenient
way to measure acidity pH - log10 H pH 7 is
neutral H OH- -gt at pH 7 H 10-7
moles/l
27
pH Plants vary pH to control many processes!
28
  • Water movement
  • Diffusion movement of single molecules down ?
    due to random motion until is even
  • Driving force?

29
  • Water movement
  • Diffusion movement of single molecules down ?
    due to random motion until is even
  • Driving force lowers free energy
  • ?G ?H- T?S

30
Water movement Diffusion movement of single
molecules down ? due to random motion until
is even Bulk Flow movement of groups
of molecules down a pressure gradient
31
  • Water movement
  • Diffusion movement of single molecules down ?
    due to random motion until is even
  • Bulk Flow movement of groups of
  • molecules down a pressure gradient
  • Independent of ? !

32
  • Water movement
  • Diffusion movement of single molecules down ?
    due to random motion until is even
  • Bulk Flow movement of groups of molecules down a
    pressure gradient
  • Independent of ? !
  • How water moves through xylem

33
  • Water movement
  • Diffusion movement of single molecules down
    due to random motion until is even
  • Bulk Flow movement of groups of molecules down a
    pressure gradient
  • Independent of ? !
  • How water moves through xylem
  • How water moves through soil and apoplast

34
  • Water movement
  • Bulk Flow movement of groups of molecules down a
    pressure gradient
  • Independent of ? !
  • How water moves through xylem
  • Main way water moves through soil and apoplast
  • Very sensitive to radius of vessel increases as
    r4

35
  • Water movement
  • Diffusion movement of single molecules down ?
    due to random motion until is even
  • Bulk Flow movement of groups of molecules down a
    pressure gradient
  • Independent of ? !
  • How water moves through xylem
  • Main way water moves through soil and apoplast
  • Very sensitive to radius of vessel increases as
    r4
  • Osmosis depends on bulk flow and diffusion!

36
Water movement Osmosis depends on bulk flow and
diffusion! water crosses membranes but other
solutes do not water tries to even its on
each side
37
Water movement Osmosis depends on bulk flow and
diffusion! water crosses membranes but other
solutes do not water tries to even its on
each side other solutes cant result is net
influx of water
38
  • Water movement
  • Osmosis depends on bulk flow and diffusion!
  • Moves through aquaporins, so rate depends on
    pressure and gradients!

39
  • Water movement
  • Osmosis depends on bulk flow and diffusion!
  • Moves through aquaporins, so rate depends on
    pressure and gradients!
  • Driving force water's free energy (J/m3 MPa)

40
  • Water potential
  • Driving force water's free energy
  • water potential Yw
  • Important for many aspects of
  • plant physiology

41
  • Water potential
  • Driving force water's free energy water
    potential Yw
  • Water moves to lower its potential

42
  • Water potential
  • Driving force water's free energy water
    potential Yw
  • Water moves to lower its potential

43
  • Water potential
  • Driving force water's free energy water
    potential Yw
  • Water moves to lower its potential
  • Depends on
  • H2O Ys (osmotic potential)

44
  • Water potential
  • Water moves to lower its potential
  • Depends on
  • H2O Ys (osmotic potential)
  • Pressure Yp
  • Turgor pressure inside cells

45
  • Water potential
  • Water moves to lower its potential
  • Depends on
  • H2O Ys (osmotic potential)
  • Pressure Yp
  • Turgor pressure inside cells
  • Negative pressure in xylem!

46
  • Water potential
  • Water moves to lower its potential
  • Depends on
  • H2O Ys (osmotic potential)
  • Pressure Yp
  • Gravity Yg
  • Yw Ys Yp Yg

47
  • Water potential
  • Water moves to lower its potential
  • Depends on
  • H2O Ys (osmotic potential)
  • Pressure Yp
  • Gravity Yg
  • Yw Ys Yp Yg
  • Yw of pure water at sea level
  • 1 atm 0 MPA

48
  • Water potential
  • Yw Ys Yp Yg
  • Yw of pure water at sea level 1 atm 0 MPA
  • Ys (osmotic potential) is always negative

49
  • Water potential
  • Yw Ys Yp Yg
  • Yw of pure water at sea level 1 atm 0 MPA
  • Ys (osmotic potential) is always negative
  • If increase solutes water will move in

50
  • Water potential
  • Yw Ys Yp Yg
  • Yw of pure water at sea level 1 atm 0 MPA
  • Ys (osmotic potential) is always negative
  • If increase solutes water will move in
  • Yp (pressure potential) can be positive or
    negative

51
  • Water potential
  • Yw Ys Yp Yg
  • Yw of pure water at sea level 1 atm 0 MPA
  • Ys (osmotic potential) is always negative
  • If increase solutes water will move in
  • Yp (pressure potential) can be positive or
    negative
  • Usually positive in cells to counteract Ys

52
  • Water potential
  • Yp (pressure potential) can be positive or
    negative
  • Usually positive in cells to counteract Ys
  • Helps plants stay same size despite daily
    fluctuations in Yw

53
  • Water potential
  • Yw Ys Yp Yg
  • Yp (pressure potential) can be positive or
    negative
  • Usually positive in cells to counteract Ys
  • Helps plants stay same size
  • despite daily fluctuations in Yw
  • Yp in xylem is negative, draws
  • water upwards

54
  • Water potential
  • Yw Ys Yp Yg
  • Yp (pressure potential) can be positive or
    negative
  • Usually positive in cells to counteract Ys
  • Helps plants stay same size
  • despite daily fluctuations in Yw
  • Yp in xylem is negative, draws
  • water upwards
  • Yg can usually be ignored, but
  • important for tall trees

55
  • Water potential
  • Measuring water potential

56
  • Water potential
  • Measuring water potential
  • Ys (osmotic potential) is easy
  • Measure concentration of solution in equilibrium
    with cells

57
  • Water potential
  • Measuring water potential
  • Ys (osmotic potential) is easy
  • Measure concentration of solution in equilibrium
    with cells
  • Yg (gravity potential) is easy height above
    ground
  • -0.01 Mpa/m

58
  • Water potential
  • Measuring water potential
  • Ys (osmotic potential) is easy
  • Measure concentration of solution in equilibrium
    with cells
  • Yg (gravity potential) is easy height above
    ground
  • YP (pressure potential) is hard!
  • Pressure bomb
  • most common technique

59
  • Water potential
  • Measuring water potential
  • Ys (osmotic potential) is easy
  • Measure concentration of solution in equilibrium
    with cells
  • Yg (gravity potential) is easy height above
    ground
  • YP (pressure potential) is hard!
  • Pressure bomb
  • most common technique
  • Others include pressure
  • transducers, xylem probes

60
  • Measuring water potential
  • YP (pressure potential) is hard!
  • Pressure bomb
  • most common technique
  • Others include pressure
  • transducers, xylem probes
  • Therefore disagree about H2O
  • transport in xylem
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