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

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

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

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

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

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

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

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

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!

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!

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

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

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?

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 ? !

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

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

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

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