Bio%20226:%20Cell%20and%20Molecular%20Biology

1

• Next assignment Mon Feb 22
• pick a biofuel, gene or condition convince the
  group in 5-10 minutes why your choice is best.
• Suggestions
• Effects of environment on biofuel production
• Drought/humidity/salinity
• pCO2
• Temperature
• Light
• Quantity
• PFD (photonflux density) intensity
• Photoperiod (daylength) duration
• Light quality color(s)
• Nutrition
• Macronutrients N, P, K, S, Ca, Mg, Fe
• Micronutrients,vitamins, adding acetate?
• 2. Effects of environment on cell walls Drought?
  inhibitors?

2

• 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!

3

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

4

• N cycle
• Most N on earth is in N2 (78 of atmosphere)
• Most N in plants is in amino acids other
  reduced forms
• Must convert N2 to a form that can be assimilated

5
Nitrogen fixation N2 8H 8e- 16 ATP ? 2NH3
H2 16ADP 16 Pi Catalysed by nitrogenase, a
very complex enzyme! Sequentially adds 2 H per
cycle until reach NH3 Also catalyzes many other
reactions
6
S assimilation SO42- comes from weathering or
from rain now an important source! Main thing
that makes rain acid!
7
S assimilation S is used in cysteine
methionine
8
S assimilation S is used in cysteine
methionine Also used in CoA, S-adenosylmethionine

9
S assimilation S is used in cysteine
methionine Also used in CoA, S-adenosylmethionine
Also used in sulphoquinovosyl-diacylglycerol
10
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)
11
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
12
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!
13
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
14
S assimilation SO4 2- is taken up by roots
transported to leaves in xylem Most is reduced
in cp
15
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
16

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

17

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

18

• 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

19

• 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

20

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

21

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

22

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

23

• 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

24

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

25

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

26

• 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

27

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

28

• S assimilation
• Most cysteine is converted to glutathione or
  methionine
• Glutamate Cysteine -gt g-glutamyl cysteine
• g-glutamyl cysteine glycine -gt glutathionine

29

• S assimilation
• Most cysteine is converted to glutathione or
  methionine
• Glutamate Cysteine -gt g-glutamyl cysteine
• g-glutamyl cysteine glycine -gt glutathionine
• Glutathione is precursor for many chemicals, eg
  phytochelatins

30

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

31

• Plant Growth
• Size shape depends on cell cell size

32
Plant Growth Size shape depends on cell
cell size Decide when,where and which way to
divide
33

• Plant Growth
• Size shape depends on cell cell size
• Decide which way to divide which way to
  elongate
• Periclinal perpendicular to surface

34

• Plant Growth
• Size shape depends on cell cell size
• Decide which way to divide which way to
  elongate
• Periclinal perpendicular to surface get longer

35

• Plant Growth
• Size shape depends on cell cell size
• Decide which way to divide which way to
  elongate
• Periclinal perpendicular to surface get longer
• Anticlinal parallel to surface

36

• Plant Growth
• Size shape depends on cell cell size
• Decide which way to divide which way to
  elongate
• Periclinal perpendicular to surface get longer
• Anticlinal parallel to surface add more layers

37

• Plant Growth
• Decide which way to divide which way to
  elongate
• Periclinal perpendicular to surface get longer
• Anticlinal parallel to surface add more layers
• Now must decide which way to elongate

38

• Plant Growth
• Decide which way to divide which way to
  elongate
• Periclinal perpendicular to surface get longer
• Anticlinal parallel to surface add more layers
• Now must decide which way to elongate which
  walls to stretch

39

• Plant Cell Walls and Growth
• Carbohydrate barrier
• surrounding cell
• Protects gives cell shape
• 1 wall made first
• mainly cellulose
• Can stretch!

40

• Plant Cell Walls and Growth
• Carbohydrate barrier
• surrounding cell
• Protects gives cell shape
• 1 wall made first
• mainly cellulose
• Can stretch!
• 2 wall made after growth
• stops
• Lignins make it tough

41

• Plant Cell Walls and Growth
• 1 wall made first
• mainly cellulose
• Can stretch! Control elongation by controlling
  orientation of cell wall fibers as wall is made

42

• Plant Cell Walls and Growth
• 1 wall made first
• mainly cellulose
• Can stretch! Control elongation by controlling
  orientation of cell wall fibers as wall is made
• 1 walls 25 cellulose, 25 hemicellulose, 35
  pectin, 5 protein (but highly variable)

43

• Plant Cell Walls and Growth
• 1 walls 25 cellulose, 25 hemicellulose, 35
  pectin, 5 protein (but highly variable)
• Cellulose ordered chains made of glucose linked
  b 1-4

44

• Plant Cell Walls and Growth
• 1 walls 25 cellulose, 25 hemicellulose, 35
  pectin, 5 protein (but highly variable)
• Cellulose ordered chains made of glucose linked
  b 1-4
• Cross-link with neighbors to form strong, stable
  fibers

45

• Plant Cell Walls and Growth
• Cellulose ordered chains made of glucose linked
  b 1-4
• Cross-link with neighbors to form strong, stable
  fibers
• Made by enzyme embedded in the plasma membrane
• Guided by cytoskeleton
• Other wall chemicals are made in Golgi secreted
• Only cellulose pattern
• is tightly controlled

46

• Plant Cell Walls and Growth
• Cellulose pattern is tightly controlled
• 6 CES enzymes form a rosette each makes 6
  chains -gt 36/fiber

47

• Plant Cell Walls and Growth
• Cellulose pattern is tightly controlled
• 6 CES enzymes form a rosette each makes 6
  chains -gt 36/fiber
• Rosettes are guided
• by microtubules

48

• Plant Cell Walls and Growth
• Cellulose pattern is tightly controlled
• 6 CES enzymes form a rosette each makes 6
  chains
• Rosettes are guided by microtubules
• Deposition pattern determines direction of
  elongation

49

• Plant Cell Walls and Growth
• Cellulose pattern is tightly controlled
• Deposition pattern determines direction of
  elongation
• New fibers are perpendicular to growth direction,
  yet fibers form a mesh

50

• Plant Cell Walls and Growth
• New fibers are perpendicular to growth direction,
  yet fibers form a mesh
• Multinet hypothesis fibers reorient as cell
  elongates
• Old fibers are anchored so gradually shift as
  cell grows

51

• Plant Cell Walls and Growth
• New fibers are perpendicular to growth direction,
  yet fibers form a mesh
• Multinet hypothesis fibers reorient as cell
  elongates
• Old fibers are anchored so gradually shift as
  cell grows
• Result mesh

52

• Plant Cell Walls and Growth
• 1 walls 25 cellulose, 25 hemicellulose, 35
  pectin, 5 protein (but highly variable)
• Hemicelluloses AKA cross-linking glycans bind
  cellulose

53

• Plant Cell Walls and Growth
• Hemicelluloses AKA cross-linking glycans bind
  cellulose
• Coat cellulose bind
• neighbor

54

• Plant Cell Walls and Growth
• Hemicelluloses AKA cross-linking glycans
• Coat cellulose bind neighbor
• Diverse group of glucans also linked b 1-4, but
  may have other sugars and components attached to
  C6

55

• Hemicelluloses
• Diverse group of glucans also linked b 1-4, but
  may have other sugars and components attached to
  C6
• makes digestion more difficult

56

• Hemicelluloses
• Diverse group of glucans also linked b 1-4, but
  may have other sugars and components attached to
  C6
• makes digestion more difficult
• Assembled in Golgi

57

• Plant Cell Walls and Growth
• Hemicelluloses AKA cross-linking glycans
• A diverse group of glucans also linked b 1-4,
  but may have other sugars and components attached
  to C6
• makes digestion more difficult
• Assembled in Golgi
• Secreted cf woven

58

• Plant Cell Walls and Growth
• 1 walls 25 cellulose, 25 hemicellulose, 35
  pectin, 5 protein (but highly variable)
• Pectins fill space between cellulose-hemicellulos
  e fibers

59

• Pectins
• Pectins fill space between cellulose-hemicellulos
  e fibers
• Form gel that determines cell wall porosity(
  makes jam)

60

• Pectins
• Pectins fill space between cellulose-hemicellulos
  e fibers
• Form gel that determines cell wall porosity (
  makes jam)
• Acidic, so also modulate pH bind polars

61

• Pectins
• Pectins fill space between cellulose-hemicellulos
  e fibers
• Form gel that determines cell wall porosity (
  makes jam)
• Acidic, so also modulate pH bind polars
• Backbone is ?1-4 linked galacturonic acid

62

• Pectins
• Backbone is ?1-4 linked galacturonic acid
• Have complex sugar side-chains, vary by spp.

63

• Pectins
• Backbone is ?1-4 linked galacturonic acid
• Have complex sugar side-chains, vary by spp.

64

• Plant Cell Walls and Growth
• Also 4 main multigenic families of structural
  proteins

65

• Plant Cell Walls and Growth
• Also 4 main multigenic families of structural
  proteins
• Amounts vary between cell types conditions

66

• Plant Cell Walls and Growth
• Also 4 main multigenic families of structural
  proteins
• Amounts vary between cell types conditions
• HRGP hydroxyproline-rich glycoproteins (eg
  extensin)
• Proline changed to hydroxyproline in Golgi

67

• Plant Cell Wall Proteins
• HRGP hydroxyproline-rich glycoproteins (eg
  extensin)
• Proline changed to hydroxyproline in Golgi
• Highly glycosylated helps bind CH2O

68

• Plant Cell Wall Proteins
• HRGP hydroxyproline-rich glycoproteins (eg
  extensin)
• Proline changed to hydroxyproline in Golgi
• Highly glycosylated helps bind CH2O
• Common in cambium, phloem

69

• Plant Cell Wall Proteins
• HRGP hydroxyproline-rich glycoproteins (eg
  extensin)
• Proline changed to hydroxyproline in Golgi
• Highly glycosylated helps bind CH2O
• Common in cambium, phloem
• Help lock the wall after growth ceases

70

• Plant Cell Wall Proteins
• HRGP hydroxyproline-rich glycoproteins (eg
  extensin)
• Proline changed to hydroxyproline in Golgi
• Highly glycosylated helps bind CH2O
• Common in cambium, phloem
• Help lock the wall after growth ceases
• Induced by wounding
• 2. PRP proline-rich proteins

71

• Plant Cell Wall Proteins
• HRGP hydroxyproline-rich glycoproteins (eg
  extensin)
• PRP proline-rich proteins
• Low glycosylation little interaction with CH2O

72

• Plant Cell Wall Proteins
• HRGP hydroxyproline-rich glycoproteins (eg
  extensin)
• PRP proline-rich proteins
• Low glycosylation little interaction with CH2O
• Common in xylem, fibers, cortex

73

• Plant Cell Wall Proteins
• HRGP hydroxyproline-rich glycoproteins (eg
  extensin)
• PRP proline-rich proteins
• Low glycosylation little interaction with CH2O
• Common in xylem, fibers, cortex
• May help lock HRGPs together

74

• Plant Cell Wall Proteins
• HRGP hydroxyproline-rich glycoproteins (eg
  extensin)
• PRP proline-rich proteins
• Low glycosylation little interaction with CH2O
• Common in xylem, fibers, cortex
• May help lock HRGPs together
• GRP Glycine-rich proteins
• No glycosylation little interaction with CH2O

75

• Plant Cell Wall Proteins
• HRGP hydroxyproline-rich glycoproteins (eg
  extensin)
• PRP proline-rich proteins
• Low glycosylation little interaction with CH2O
• Common in xylem, fibers, cortex
• May help lock HRGPs together
• GRP Glycine-rich proteins
• No glycosylation little interaction with CH2O
• Common in xylem

76

• Plant Cell Wall Proteins
• HRGP hydroxyproline-rich glycoproteins (eg
  extensin)
• PRP proline-rich proteins
• Low glycosylation little interaction with CH2O
• Common in xylem, fibers, cortex
• May help lock HRGPs together
• GRP Glycine-rich proteins
• No glycosylation little interaction with CH2O
• Common in xylem
• May help lock HRGPs PRPs together

77

• Plant Cell Wall Proteins
• HRGP hydroxyproline-rich glycoproteins (eg
  extensin)
• PRP proline-rich proteins
• GRP Glycine-rich proteins
• No glycosylation little interaction with CH2O
• Common in xylem
• May help lock HRGPs PRPs together
• 4. Arabinogalactan proteins

78

• Plant Cell Wall Proteins
• HRGP hydroxyproline-rich glycoproteins (eg
  extensin)
• PRP proline-rich proteins
• GRP Glycine-rich proteins
• Arabinogalactan proteins
• Highly glycosylated helps bind CH2O

79

• Plant Cell Wall Proteins
• HRGP hydroxyproline-rich glycoproteins (eg
  extensin)
• PRP proline-rich proteins
• GRP Glycine-rich proteins
• Arabinogalactan proteins
• Highly glycosylated helps bind CH2O
• Anchored to PM by GPI

80

• Plant Cell Wall Proteins
• HRGP hydroxyproline-rich glycoproteins (eg
  extensin)
• PRP proline-rich proteins
• GRP Glycine-rich proteins
• Arabinogalactan proteins
• Highly glycosylated helps bind CH2O
• Anchored to PM by GPI
• Help cell adhesion and cell signaling

81

• Plant Cell Wall Proteins
• HRGP hydroxyproline-rich glycoproteins (eg
  extensin)
• PRP proline-rich proteins
• GRP Glycine-rich proteins
• Arabinogalactan proteins
• Highly glycosylated helps bind CH2O
• Anchored to PM by GPI
• Help cell adhesion and cell signaling
• 5. Also many enzymes involved in cell wall
  synthesis and loosening

82

• Plant Cell Walls and Growth
• Also many enzymes involved in cell wall synthesis
  and loosening
• As growth stops, start making lignins linking
  HGRP

83

• Plant Cell Walls and Growth
• As growth stops, start depositing lignins
  linking HGRP
• Lignins polyphenolic macromolecules 2nd most
  abundant on earth (after cellulose)

84

• Plant Cell Walls and Growth
• Lignins polyphenolic macromolecules 2nd most
  abundant on earth (after cellulose)
• Bond hemicellulose solidify protect cell wall
  (natures cement) very difficult to digest

85

• Plant Cell Walls and Growth
• Lignins polyphenolic macromolecules 2nd most
  abundant on earth (after cellulose)
• Bond hemicellulose solidify protect cell wall
  (natures cement) very difficult to digest
• Monomers are made in cytoplasm secreted

86

• Plant Cell Walls and Growth
• Monomers are made in cytoplasm secreted
• Peroxidase laccase in cell wall create radicals
  that polymerise non-enzymatically

87

• Plant Cell Walls and Growth
• Monomers are made in cytoplasm secreted
• Peroxidase laccase in cell wall create radicals
  that polymerise non-enzymatically

88

• Plant Cell Walls and Growth
• Peroxidase laccase in cell wall create radicals
  that polymerise non-enzymatically
• Very difficult to digest, yet major plant
  component!

89

• Plant Cell Walls and Growth
• As growth stops, start depositing lignins
  linking HGRP
• Solidify protect cell wall very difficult to
  digest
• Elongation precedes lignification

90

• Plant Cell Walls and Growth
• As growth stops, start depositing lignins
  linking HGRP
• Solidify protect cell wall very difficult to
  digest
• Elongation precedes lignification
• Requires loosening the bonds joining the cell wall

91

• Plant Cell Walls and Growth
• Elongation precedes lignification
• Requires loosening the bonds joining the cell
  wall
• Cant loosen too much or cell will burst

92

• Plant Cell Walls and Growth
• Elongation precedes lignification
• Requires loosening the bonds joining the cell
  wall
• Cant loosen too much or cell will burst
• Must coordinate with cell wall synthesis so wall
  stays same

93

• Plant Cell Walls and Growth
• Elongation loosening the bonds joining the cell
  wall
• Cant loosen too much or cell will burst
• Must coordinate with cell wall synthesis so wall
  stays same
• Must weaken crosslinks joining cellulose fibers

94

• Plant Cell Walls and Growth
• Must weaken crosslinks joining cellulose fibers
• Turgor pressure then makes cells expand

95

• Plant Cell Walls and Growth
• Must weaken crosslinks joining cellulose fibers
• Turgor pressure then makes cells expand
• Lower pH many studies show that lower pH is
  sufficient for cell elongation

96

• Plant Cell Walls and Growth
• Must weaken crosslinks joining cellulose fibers
• Lower pH many studies show that lower pH is
  sufficient for cell elongation
• Acid growth hypothesis Growth regulators cause
  elongation by activating H pump

97

• Plant Cell Walls and Growth
• Acid growth hypothesis Growth regulators cause
  elongation by activating H pump
• Inhibitors of H pump stop elongation
• But Cosgrove isolated proteins that loosen cell
  wall
• Test protein extracts
• to see if wall loosens

98

• Plant Cell Walls and Growth
• Acid growth hypothesis Growth regulators cause
  elongation by activating H pump
• But Cosgrove isolated proteins that loosen cell
  wall
• Test protein extracts to see if wall loosens
• Identified expansin proteins that enhance acid
  growth

99

• Plant Cell Walls and Growth
• Acid growth hypothesis Growth regulators cause
  elongation by activating H pump
• But Cosgrove isolated proteins that loosen cell
  wall
• Test protein extracts to see if wall loosens
• Identified expansin proteins that enhance acid
  growth
• Still dont know how they work!

100

• Plant Cell Walls and Growth
• Identified expansin proteins that enhance acid
  growth
• Still dont know how they work!
• Best bet, loosen hemicellulose/cellulose bonds

101

• Plant Cell Walls and Growth
• Also have endoglucanases and transglucanases that
  cut reorganize hemicellulose pectin

102

• Plant Cell Walls and Growth
• Also have endoglucanases and transglucanases that
  cut reorganize hemicellulose pectin
• XET (xyloglucan endotransglucosylase) is
  best-known

103

• Plant Cell Walls and Growth
• Also have endoglucanases and transglucanases that
  cut reorganize hemicellulose pectin
• XET (xyloglucan endotransglucosylase) is
  best-known
• Cuts rejoins hemicellulose
• in new ways

104

• Plant Cell Walls and Growth
• XET is best-known
• Cuts rejoins hemicellulose
• in new ways
• Expansins XET catalyse cell
• wall creepage

105

• Plant Cell Walls and Growth
• XET is best-known
• Cuts rejoins hemicellulose in new ways
• Expansins XET catalyse cell wall creepage
• Updated acid growth hypothesis main function of
  lowering pH is activating expansins and glucanases

106

• Plant Cell Walls and Growth
• Updated acid growth hypothesis main function of
  lowering pH is activating expansins and
  glucanases
• Coordinated with synthesis of new cell wall to
  keep thickness constant

107

• Plant Cell Walls and Signaling
• Pathogens must digest cell wall to enter plant

108

• Plant Cell Walls and Signaling
• Pathogens must digest cell wall to enter plant
• Release cell wall fragments

109

• Plant Cell Walls and Signaling
• Pathogens must digest cell wall to enter plant
• Release cell wall fragments
• Many oligosaccharides signalHELP!

110

• Plant Cell Walls and Signaling
• Pathogens must digest cell wall to enter plant
• Release cell wall fragments
• Many oligosaccharides signalHELP!
• Elicit plant defense responses