Bio 226: Cell and Molecular Biology

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• Plan C
• Pick a problem
• Pick some plants to study
• Design some experiments
• See where they lead us

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• Biofuels
• What would make a good biofuel?
• How and where to grow it?
• Can we get plants to make diesel, H2 (g) or
  electricity?
• Climate/CO2 change
• How will plants be affected?
• Can we use plants to help alleviate it?
• Stress responses/stress avoidance
• Structural
• Biochemical (including C3 vs C4 vs CAM)
• Other (dormancy, carnivory, etc)
• Plant products
• Improving food production
• Phytoremediation
• Plant signaling (including neurobiology)
• Something else?

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Endomembrane system Organelles derived from the
ER 1) ER 2) Golgi 3) Vacuoles 4)
Plasma Membrane 5) Nuclear Envelope 6)
Endosomes 7) Oleosomes
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GOLGI COMPLEX Individual, flattened stacks of
membranes made from ER Fn post office collect
ER products, process deliver them Altered in
each stack Makes most cell wall
carbohydrates! Proteins address is built in
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VACUOLES Derived from Golgi Fns 1)digestion a)
Organelles b) food particles
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VACUOLES Derived from Golgi Fns 1)digestion a)
Organelles b) food particles 2) storage
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VACUOLES Derived from Golgi Fns 1) digestion a)
Organelles b) food particles 2) storage 3)
turgor push plasma membrane against cell wall
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VACUOLES Vacuoles are subdivided lytic vacuoles
are distinct from storage vacuoles!
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Endomembrane system Organelles derived from the
ER 1) ER 2) Golgi 3) Vacuoles 4)
Plasma Membrane Regulates transport in/out of
cell
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Endomembrane system Organelles derived from the
ER 1) ER 2) Golgi 3) Vacuoles 4)
Plasma Membrane Regulates transport in/out of
cell Lipids form barrier Proteins
transport objects info
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Endomembrane System 5) Nuclear envelope
regulates transport in/out of nucleus Continuous
with ER
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Endomembrane System 5) Nuclear enveloperegulates
transport in/out of nucleus Continuous with
ER Transport is only through nuclear pores
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Endomembrane System 5) Nuclear enveloperegulates
transport in/out of nucleus Continuous with
ER Transport is only through nuclear pores Need
correct signal receptor for import
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Endomembrane System 5) Nuclear envelope
regulates transport in/out of nucleus Continuous
with ER Transport is only through nuclear
pores Need correct signal receptor for import
new one for export
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Endomembrane System Endosomes vesicles derived
from Golgi or Plasma membrane Fn sorting
materials recycling receptors
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Endomembrane System Oleosomes oil storage bodies
derived from SER Surrounded by lipid monolayer!
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• Endomembrane System
• Oleosomes oil storage bodies derived from SER
• Surrounded by lipid monolayer!
• filled with lipids no internal hydrophobic
  effect!

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• endosymbionts
• derived by division of preexisting organelles
• no vesicle transport
• Proteins lipids are not glycosylated

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• endosymbionts
• derived by division of preexisting organelles
• little exchange of membranes with other
  organelles
• 1) Peroxisomes (microbodies)

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Peroxisomes (microbodies) 1 membrane
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Peroxisomes (microbodies) found in (nearly) all
eukaryotes 1 membrane Fn 1) destroy H2O2, other
O2-related poisons
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• Peroxisomes
• Fn
• destroy H2O2, other O2-related poisons
• change fat to CH2O (glyoxysomes)

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• Peroxisomes
• Fns
• destroy H2O2, other
• O2-related poisons
• change fat to CH2O
• (glyoxysomes)
• Detoxify recycle
• photorespiration products

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• Peroxisomes
• Fn
• destroy H2O2, other O2-related poisons
• change fat to CH2O (glyoxysomes)
• Detoxify recycle photorespiration products
• Destroy EtOH (made in anaerobic roots)

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Peroxisomes ER can make peroxisomes under special
circumstances! e.g. peroxisome-less mutants can
restore peroxisomes when the wild-type gene is
restored
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endosymbionts 1) Peroxisomes (microbodies) 2)
Mitochondria
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Mitochondria Bounded by 2 membranes
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Mitochondria 2 membranes Smooth OM
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Mitochondria 2 membranes Smooth OM IM folds into
cristae
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Mitochondria -gt 4 compartments 1) OM 2)
intermembrane space 3) IM 4) matrix
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Mitochondria matrix contains DNA, RNA and
ribosomes
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Mitochondria matrix contains DNA, RNA and
ribosomes Genomes vary from 100,000 to 2,500,000
bp, but only 40-43 genes
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Mitochondria matrix contains DNA, RNA and
ribosomes Genomes vary from 100,000 to 2,500,000
bp, but only 40-43 genes Reproduce by fission
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Mitochondria matrix contains DNA, RNA and
ribosomes Genomes vary from 100,000 to 2,500,000
bp, but only 40-43 genes Reproduce by fission IM
is 25 cardiolipin, a bacterial phospholipid
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Mitochondria Genomes vary from 100,000 to
2,500,000 bp, but only 40-43 genes Reproduce by
fission IM is 25 cardiolipin, a bacterial
phospholipid Genes most related to Rhodobacteria
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Mitochondria Fn cellular respiration -gt
oxidizing food supplying energy to cell Also
make many important biochemicals
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Mitochondria Fn cellular respiration -gt
oxidizing food supplying energy to cell Also
make important biochemicals help recycle PR
products
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• endosymbionts
• Peroxisomes
• Mitochondria
• 3) Plastids

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Plastids Chloroplasts do photosynthesis Amyloplast
s store starch Chromoplasts store
pigments Leucoplasts are found in roots
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Chloroplasts Bounded by 2 membranes 1) outer
envelope 2) inner envelope
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• Chloroplasts
• Interior stroma
• Contains thylakoids
• membranes where light
• rxns of photosynthesis occur
• mainly galactolipids

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• Chloroplasts
• Interior stroma
• Contains thylakoids
• membranes where light rxns of photosynthesis
  occur
• mainly galactolipids
• Contain DNA, RNA, ribosomes

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Chloroplasts Contain DNA, RNA, ribosomes 120,000-1
60,000 bp, 100 genes
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Chloroplasts Contain DNA, RNA, ribosomes 120,000-1
60,000 bp, 100 genes Closest relatives
cyanobacteria
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Chloroplasts Contain DNA, RNA, ribosomes 120,000-1
60,000 bp, 100 genes Closest relatives
cyanobacteria Divide by fission
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Chloroplasts Contain DNA, RNA, ribosomes 120,000-1
60,000 bp, 100 genes Closest relatives
cyanobacteria Divide by fission Fns
Photosynthesis
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Chloroplasts Fns Photosynthesis starch
synth Photoassimilation of N S
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Chloroplasts Fns Photosynthesis starch
synth Photoassimilation of N S Fatty acid
some lipid synth
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Chloroplasts Fns Photosynthesis starch
synth Photoassimilation of N S Fatty acid
some lipid synth Synth of ABA, GA, many other
biochem
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Chloroplasts Mitochondria Contain eubacterial
DNA, RNA, ribosomes Inner membranes have
bacterial lipids Divide by fission Provide best
support for endosymbiosis
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Endosymbiosis theory (Margulis) Archaebacteria
ate eubacteria converted them to symbionts
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Endosymbiosis theory (Margulis) Archaebacteria
ate eubacteria converted them to symbionts
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Endosymbiosis theory (Margulis) Archaebacteria
ate eubacteria converted them to symbionts
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cytoskeleton network of proteins which give
cells their shape also responsible for shape of
plant cells because guide cell wall
formation left intact by detergents that extract
rest of cell
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Cytoskeleton Actin fibers (microfilaments) 7 nm
diameter Form 2 chains of polar actin subunits
arranged in a double helix
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• Actin fibers
• polar subunits arranged in a double helix
• Add to end
• Fall off - end
• Fn movement

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Actin fibers Very conserved in evolution Fn
motility Often with myosin
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Actin fibers Very conserved in evolution Fn
motility Often with myosin responsible for
cytoplasmic streaming
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Actin fibers Very conserved in evolution Fn
motility Often with myosin responsible for
cytoplasmic streaming, Pollen tube growth
movement through plasmodesmata
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Actin fibers Often with myosin responsible for
cytoplasmic streaming, Pollen tube growth
movement through plasmodesmata
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Intermediate filaments Protein fibers 8-12 nm dia
(between MFs MTs) form similar looking
filaments Conserved central, rod-shaped ?-helical
domain
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Intermediate filaments 2 monomers form dimers
with parallel subunits Dimers form
tetramers aligned in opposite orientations
staggered
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Intermediate filaments 2 monomers form dimers
with parallel subunits Dimers form
tetramers Tetramers form IF
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Intermediate filaments 2 monomers form dimers
with parallel subunits Dimers form
tetramers Tetramers form IF Plants have
several Fn unclear
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Microtubules Hollow, cylindrical found in most
eukaryotes outer diameter - 24 nm wall thickness
- 5 nm Made of 13 longitudinal rows of
protofilaments
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Microtubules Made of a???b tubulin subunits
polymerize to form protofilaments (PF) PF form
sheets Sheets form microtubules
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Microtubules Protofilaments are polar ?-tubulin
_at_ - end ?-tubulin _at_ end all in single MT have
same polarity
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Microtubules In constant flux polymerizing
depolymerizing Add to ? () Fall off ? (-)
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Microtubules Control growth by controlling rates
of assembly disassembly because these are
distinct processes can be controlled
independently! Colchicine makes MTs
disassemble Taxol prevents disassembly
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Microtubules Control growth by controlling rates
of assembly disassembly Are constantly
rearranging inside plant cells!
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• Microtubules
• Control growth by controlling rates of assembly
  disassembly
• Are constantly rearranging inside plant cells!
• during mitosis cytokinesis

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• Microtubules
• Control growth by controlling rates of assembly
  disassembly
• Are constantly rearranging inside plant cells!
• during mitosis cytokinesis
• Guide formation of cell plate of walls in
  interphase

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µT Assembly µTs always emerge from
Microtubule-Organizing Centers (MTOC)
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µT Assembly µTs always emerge from
Microtubule-Organizing Centers (MTOC) patches of
material at outer nuclear envelope
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• Microtubules
• MAPs (Microtubule Associated Proteins) may
• stabilize ?tubules
• alter rates of
• assembly/disassembly
• crosslink adjacent
• ?tubules
• link cargo

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2 classes of molecular motors 1) Kinesins move
cargo to µT plus end 2) Dyneins move cargo to
minus end Walk hand-over-hand towards chosen
end
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• µT functions
• Give cells shape by guiding cellulose synth

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• µT functions
• Give cells shape by guiding cellulose synth
• Anchor organelles

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• µT functions
• Give cells shape by guiding cellulose synth
• Anchor organelles
• Intracellular motility