Bio 226: Cell and Molecular Biology

1

• Water uptake
• Path starts at root hairs
• Must take water from soil
• Ease depends on availability how tightly it is
  bound
• Binding depends on particle size chem

2

• Water uptake
• Availability depends on amount in soil pores
• Saturation completely full
• Field capacity amount left after gravity has
  drained excess
• Permanent wilting point amount where soil water
  potential is too negative for plants to take it up

3

• Plant Stress
• Water?
• Nutrients?
• Environment?
• Temp?
• Pollution?
• Ozone, other gases?
• Herbicides, eg Round-Up, Atrazine?
• Insects and other herbivores?
• Pathogens bacteria, viruses, fungi
• Salinity

4
Plant Stress Next assignment presenting a plant
stressor, what is known about it, and why it
might affect plant 2 compounds in an 10 minute
presentation? Alternative presenting another
good plant/stressor response to study and why we
should choose it over the ones already presented.
5
(No Transcript)
6
(No Transcript)
7
(No Transcript)
8

• Mineral Nutrition
• Nutrients in soil
• Plants alter pH _at_ roots to aid uptake
• Also use symbionts
• Mycorrhizal fungi help especially with P
• Some plants form symbioses with N-fixing prok.

9

• Nutrient uptake
• Most nutrients are dissolved in water
• Enter root through apoplast until hit endodermis
• Then must cross plasma membrane

10

• Nutrient uptake
• Then must cross plasma membrane
• Gases, small uncharged non-polar molecules
  diffuse
• down their ?
• Important for CO2, auxin NH3 transport

11
Selective Transport 1) Channels integral membrane
proteins with pore that specific ions diffuse
through
12
Selective Transport 1) Channels 2) Facilitated
Diffusion (carriers) Carrier binds molecule
13

• 4 classes of Active transport ATPase proteins
• 1) P-type ATPases (P phosphorylation)
• 2) V-type ATPases (V vacuole)
• 3) F-type ATPases (F factor)
• 4) ABC ATPases (ABC ATP Binding Cassette)
• multidrug resistance proteins

14
Secondary active transport Uses ? created by
active transport to pump something else across a
membrane against its ?
15
Nutrient uptake Gases enter/exit by diffusion
down their ? Ions vary dramatically!
16
Nutrient uptake Gases enter/exit by diffusion
down their ? Ions vary dramatically! H is
actively pumped out of cell by P-type H -ATPase
17
Nutrient uptake Ions vary dramatically! H is
actively pumped out of cell by P-type H
-ATPase and into vacuole by V-type ATPase PPase
18

• Nutrient uptake
• H is actively pumped out of cell by P-type H
  -ATPase
• and into vacuole by V-type ATPase PPase
• Main way plants make membrane potential (?Em)!

19

• Nutrient uptake
• H is actively pumped out of cell by P-type H
  -ATPase
• and into vacuole by V-type ATPase PPase
• Main way plants make membrane potential (?Em)!
• Used for many kinds of transport!

20
Nutrient uptake Many ions are imported by
multiple transporters with varying affinities
21

• Nutrient uptake
• Many ions are imported by multiple transporters
  with varying affinities
• K diffuses through channels down ?Em low
  affinity

22

• Nutrient uptake
• Many ions are imported by multiple transporters
  with varying affinities
• K diffuses through channels down ?Em low
  affinity
• Also taken up by H symporters high affinity

23

• Nutrient uptake
• Many ions are imported by multiple transporters
  with varying affinities
• K diffuses through channels down ?Em low
  affinity
• Also taken up by H symporters high affinity
• Low affinity is cheaper
• but less effective

24
Nutrient uptake K diffuses through channels down
?Em low affinity Also taken up by H symporters
high affinity Low affinity is cheaper but less
effective some channels also transport Na
25
Nutrient uptake K diffuses through channels down
?Em low affinity Also taken up by H symporters
high affinity Low affinity is cheaper but less
effective some channels also transport Na why
Na slows K uptake?
26
Nutrient uptake K diffuses through channels down
?Em low affinity Also taken up by H symporters
high affinity Low affinity is cheaper but less
effective some channels also transport Na why
Na slows K uptake? Na is also expelled by H
antiport
27

• Nutrient uptake
• Na is also expelled
• by H antiport
• Enters through channels
• Ca2 is expelled by P-type
• ATPases in PM

28

• Nutrient uptake
• Ca2 is expelled by P-type ATPases in PM
• pumped into vacuole ER by H antiport
  P-type

29

• Nutrient uptake
• Ca2 is expelled by P-type ATPases in PM
• pumped into vacuole ER by H antiport P-type
• enters cytosol via gated channels

30

• Nutrient uptake
• PO43-, SO42-, Cl- NO3-
• enter by H symport

31

• Nutrient uptake
• PO43-, SO42-, Cl- NO3- enter by H symport
• also have anion transporters of ABC type

32

• Nutrient uptake
• PO43-, SO42-, Cl- NO3- enter by H symport
• also have anion transporters of ABC type
• and anion channels

33

• Nutrient uptake
• PO43-, SO42-, Cl- NO3- enter by H symport
• also have anion transporters of ABC type
• and anion channels
• Plants take up N many ways

34

• Nutrient uptake
• Plants take up N many ways NO3- NH4 are
  main forms

35

• Nutrient uptake
• Plants take up N many other ways
• NO3- also by channels
• NH3 by diffusion
• NH4 by carriers

36

• Nutrient uptake
• Plants take up N many other ways
• NO3- by channels
• NH3 by diffusion
• NH4 by carriers
• NH4 by channels

37

• Nutrient uptake
• Plants take up N many other ways
• 3 families of H symporters take up amino acids

38

• Nutrient uptake
• Plants take up N many other ways
• 3 families of H symporters take up amino acids
• Also have many peptide transporters
• some take up di- tri-
• peptides by H symport

39

• Nutrient uptake
• Plants take up N many other ways
• 3 families of H symporters take up amino acids
• Also have many peptide transporters
• some take up di- tri-
• peptides by H symport
• others take up tetra-
• penta-peptides by H symport

40

• Nutrient uptake
• Plants take up N many other ways
• 3 families of H symporters take up amino acids
• Also have many peptide transporters
• some take up di- tri-
• peptides by H symport
• others take up tetra-
• penta-peptides by H symport
• Also have ABC transporters
• that import peptides

41

• Nutrient uptake
• Plants take up N many other ways
• 3 families of H symporters take up amino acids
• Also have many peptide transporters
• some take up di- tri-
• peptides by H symport
• others take up tetra-
• penta-peptides by H symport
• Also have ABC transporters
• that import peptides
• N is vital!
• NO3- NH4 are main forms

42

• Nutrient uptake
• Metals are taken up by ZIP proteins by ABC
  transporters
• same protein may import Fe, Zn Mn!

43
Nutrient uptake Much is coupled to pH gradient
44
Nutrient transport in roots Move from soil to
endodermis in apoplast
45
Nutrient transport in roots Move from soil to
endodermis in apoplast Move from endodermis to
xylem in symplast
46
Nutrient transport in roots Move from endodermis
to xylem in symplast Transported into xylem by H
antiporters
47
Nutrient transport in roots Move from endodermis
to xylem in symplast Transported into xylem by H
antiporters, channels
48
Nutrient transport in roots Transported into
xylem by H antiporters, channels,pumps
49
Nutrient transport in roots Transported into
xylem by H antiporters, channels,pumps Lowers
xylem water potential -gt root pressure
50
Water Transport Passes water nutrients to
xylem Ys of xylem makes root pressure Causes
guttation pumping water into shoot
51
Transport to shoot Nutrients move up plant in
xylem sap
52
Nutrient transport in leaves Xylem sap moves
through apoplast Leaf cells take up what they
want
53

• Nutrient assimilation
• Assimilating N and S is
• very expensive!
• Reducing NO3- to NH4
• costs 8 e- (1 NADPH
• 6 Fd)

54

• Nutrient assimilation
• Assimilating N and S is
• very expensive!
• Reducing NO3- to NH4
• costs 8 e- (1 NADPH
• 6 Fd)
• Assimilating NH4 into
• amino acids also costs
• ATP e-

55

• Nutrient assimilation
• Assimilating N and S is very expensive!
• Reducing NO3- to NH4 costs 8 e- (1 NADPH 6 Fd)
• Assimilating NH4 into amino acids also costs ATP
  e-
• Nitrogen fixation costs 16 ATP 8 e-

56

• Nutrient assimilation
• Assimilating N and S is very expensive!
• Reducing NO3- to NH4 costs 8 e- (1 NADPH 6 Fd)
• Assimilating NH4 into amino acids also costs ATP
  e-
• Nitrogen fixation costs 16 ATP 8 e-
• SO42- reduction to S2- costs 8 e- 2ATP

57

• Nutrient assimilation
• Assimilating N and S is very expensive!
• Reducing NO3- to NH4 costs 8 e- (1 NADPH 6 Fd)
• Assimilating NH4 into amino acids also costs ATP
  e-
• Nitrogen fixation costs 16 ATP 8 e-
• SO42- reduction to S2- costs 8 e- 2ATP
• S2- assimilation into Cysteine costs 2 more e-
• Most explosives are based on N or S!

58

• Nutrient assimilation
• Most explosives are based on N or S!
• Most nutrient assimilation occurs in source
  leaves!

59

• N cycle
• Must convert N2 to a form that can be assimilated
• N2 -gt NO3- occurs in atmosphere lightning (8)
  Photochemistry (2) of annual total fixed
• Remaining 90 comes from biological fixation to
  NH4

60

• N cycle
• Soil bacteria denitrify NO3- NH4 back to N2
• Plants must act fast!
• Take up NO3- NH4 but generally prefer NO3-
• Main form available due to bacteria

61
N assimilation by non-N fixers Nitrate reductase
in cytoplasm reduces NO3- to NO2- NO3- NADPH
NO2- NADP large enzyme with FAD Mo
cofactors NO2- is imported to plastids
reduced to NH4 by nitrite reductase
62
N assimilation by non-N fixers NO2- is imported
to plastids reduced to NH4 by nitrite
reductase NO2- 6 Fdred 8 H NH4 6 Fdox
2 H2O 0.2 of NO2- is released as N2O
another reason rape corn biofuels increase
global warming
63
N assimilation by non-N fixers NO2- is imported
to plastids reduced to NH4 by nitrite
reductase NO2- 6 Fdred 8 H NH4 6 Fdox
2 H2O 0.2 of NO2- is released as N2O
another reason rape corn biofuels increase
global warming Regulated at NO3- reductase
always ltlt NO2- reductase NO2- is toxic!
64
N assimilation by non-N fixers Regulated at NO3-
reductase always ltlt NO2- reductase NO2- is
toxic! NR induced by light nitrate
65
N assimilation by non-N fixers Regulated at NO3-
reductase always ltlt NO2- reductase NO2- is
toxic! NR induced by light nitrate Regulated by
kinase in dark, dephosphorylation in day
66

• NH4 assimilation
• GS -gt GOGAT
• Glutamate NH4 ATP ltgt Glutamine ADP Pi

67

• GS -gt GOGAT
• Glutamate NH4 ATP ltgt Glutamine ADP Pi
• Glutamine a-ketoglutarate NADH/2 Fdred ltgt
• 2 Glutamate NAD/ 2 Fdox

68

• GS -gt GOGAT
• Glutamate NH4 ATP ltgt Glutamine ADP Pi
• Glutamine a-ketoglutarate NADH/2 Fdred ltgt
• 2 Glutamate NAD/ 2 Fdox
• 3. Fd GOGAT lives in source cp

69

• GS -gt GOGAT
• Fd GOGAT lives in source cp
• NADH GOGAT lives in sinks

70

• GS -gt GOGAT
• Glutamate NH4 ATP ltgt Glutamine ADP Pi
• Glutamine a-ketoglutarate NADH/2 Fdred ltgt
• 2 Glutamate NAD/ 2 Fdox
• 3. Use glutamate to make other a.a. by
  transamination

71

• GS -gt GOGAT
• 3. Use glutamate to make other a.a. by
  transamination
• Glutamate, aspartate alanine can be converted
  to the other a.a.

72
S assimilation SO42- comes from weathering or
from rain now an important source! Main thing
that makes rain acid!
73
S assimilation S is used in cysteine
methionine
74
S assimilation S is used in cysteine
methionine Also used in CoA, S-adenosylmethionine

75
S assimilation S is used in cysteine
methionine Also used in CoA, S-adenosylmethionine
Also used in sulphoquinovosyl-diacylglycerol
76
S assimilation S is used in cysteine
methionine Also used in CoA, S-adenosylmethionine
Also used in sulphoquinovosyl-diacylglycerol And
in many storage compounds eg allicin (garlic)
77
S assimilation SO42- comes from weathering or
from rain now an important source! Main thing
that makes rain acid! Some bacteria use SO42- as
e- acceptor -gt H2S
78
S assimilation SO42- comes from weathering or
from rain now an important source! Main thing
that makes rain acid! Some bacteria use SO42- as
e- acceptor -gt H2S Some photosynthetic bacteria
use reduced S as e- donor!
79
S assimilation SO42- comes from weathering or
from rain now an important source! Main thing
that makes rain acid! Some bacteria use SO42- as
e- acceptor -gt H2S Some photosynthetic bacteria
use reduced S as e- donor! Now that acid rain has
declined in N. Europe Brassica wheat need S in
many places
80
S assimilation SO4 2- is taken up by roots
transported to leaves in xylem Most is reduced
in cp
81
S assimilation SO4 2- is taken up by roots
transported to leaves in xylem Most is reduced
in cp 1. add SO4 2- to ATP -gt APS
82

• S assimilation
• add SO4 2- to ATP -gt APS
• Transfer S to Glutathione -gt S-sulfoglutathione

83

• S assimilation
• add SO4 2- to ATP -gt APS
• Transfer S to Glutathione -gt S-sulfoglutathione
• S-sulfoglutathione GSH -gt SO32- GSSG

84

• S assimilation
• add SO4 2- to ATP -gt APS
• Transfer S to Glutathione -gt S-sulfoglutathione
• S-sulfoglutathione GSH -gt SO32- GSSG
• Sulfite 6 Fd -gt Sulfide

85

• S assimilation
• add SO4 2- to ATP -gt APS
• Transfer S to Glutathione -gt S-sulfoglutathione
• S-sulfoglutathione GSH -gt SO32- GSSG
• Sulfite 6 Fd -gt Sulfide
• Sulfide O-acetylserine -gt cysteine acetate
• O-acetylserine was made from serine acetyl-CoA

86

• S assimilation
• Most cysteine is converted to
• glutathione or methionine

87

• S assimilation
• Most cysteine is converted to
• glutathione or methionine
• Glutathione is main form
• exported

88

• S assimilation
• Most cysteine is converted to
• glutathione or methionine
• Glutathione is main form
• exported
• Also used to make many other
• S-compounds

89

• S assimilation
• Most cysteine is converted to
• glutathione or methionine
• Glutathione is main form
• exported
• Also used to make many other
• S-compounds
• Methionine also has many uses
• besides protein synthesis

90

• S assimilation
• Most cysteine is converted to glutathione or
  methionine
• Cys homoserine -gt cystathione

91

• S assimilation
• Most cysteine is converted to glutathione or
  methionine
• Cys homoserine -gt cystathione
• Cystathione -gt homocysteine Pyruvate NH4

92

• S assimilation
• Most cysteine is converted to glutathione or
  methionine
• Cys homoserine -gt cystathione
• Cystathione -gt homocysteine Pyruvate NH4
• Homocysteine CH2THF -gt Met THF
• 80 of met is converted to S-adenosylmethionine
  used for biosyntheses

93

• S assimilation
• Most cysteine is converted to glutathione or
  methionine
• Glutathione is made enzymatically!
• Glutamate Cysteine -gt g-glutamyl cysteine

94

• S assimilation
• Glutathione (GluCysGly) is made enzymatically!
• Glutamate Cysteine -gt g-glutamyl cysteine
• g-glutamyl cysteine glycine -gt glutathionine

95

• S assimilation
• Glutathione (GluCysGly) is made enzymatically!
• Glutamate Cysteine -gt g-glutamyl cysteine
• g-glutamyl cysteine glycine -gt glutathionine
• Glutathione is precursor for many chemicals, eg
  phytochelatins

96

• S assimilation
• Glutathione (GluCysGly) is made enzymatically!
• Glutamate Cysteine -gt g-glutamyl cysteine
• g-glutamyl cysteine glycine -gt glutathionine
• Glutathione is precursor for many chemicals, eg
  phytochelatins
• SAM glutathione are also precursors for many
  cell wall components

97
Assignment 1 Pick a secondary compound and figure
out how to measure it
98
Assignment 2 Design a way to see how plants are
responding to the stress