Plan C 1.Pick a problem 2.Pick some plants to study 3.Design some experiments 4.See where they lead us

1.Biofuels What would make a good biofuel? How and where to grow it? Can we get plants to make diesel, H 2 (g) or electricity? 2.Climate/CO 2 change How will plants be affected? Can we use plants to help alleviate it? 3.Stress responses/stress avoidance Structural Biochemical (including C3 vs C4 vs CAM) Other (dormancy, carnivory, etc) 4.Plant products 5.Improving food production 6.Phytoremediation 7.Plant signaling (including neurobiology) 8.Something else?

Endomembrane system Organelles derived from the ER 1) ER 2) Golgi 3) Vacuoles 4) Plasma Membrane 5) Nuclear Envelope 6) Endosomes 7) Oleosomes

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! Protein’s address is built in

VACUOLES Derived from Golgi; Fns: 1)digestion a) Organelles b) food particles

VACUOLES Derived from Golgi; Fns: 1)digestion a) Organelles b) food particles 2) storage

VACUOLES Derived from Golgi; Fns: 1) digestion a) Organelles b) food particles 2) storage 3) turgor: push plasma membrane against cell wall

VACUOLES Vacuoles are subdivided: lytic vacuoles are distinct from storage vacuoles!

Endomembrane system Organelles derived from the ER 1) ER 2) Golgi 3) Vacuoles 4) Plasma Membrane Regulates transport in/out of cell

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

Endomembrane System 5) Nuclear envelope: regulates transport in/out of nucleus Continuous with ER

Endomembrane System 5) Nuclear envelope:regulates transport in/out of nucleus Continuous with ER Transport is only through nuclear pores

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

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

Endomembrane System Endosomes: vesicles derived from Golgi or Plasma membrane Fn: sorting materials & recycling receptors

Endomembrane System Oleosomes: oil storage bodies derived from SER Surrounded by lipid monolayer!

Endomembrane System Oleosomes: oil storage bodies derived from SER Surrounded by lipid monolayer! filled with lipids: no internal hydrophobic effect!

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

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

Peroxisomes (microbodies) 1 membrane

Peroxisomes (microbodies) found in (nearly) all eukaryotes 1 membrane Fn: 1) destroy H 2 O 2, other O 2 -related poisons

Peroxisomes Fn: 1.destroy H 2 O 2, other O 2 -related poisons 2.change fat to CH 2 O (glyoxysomes)

Peroxisomes Fns: 1.destroy H 2 O 2, other O 2 -related poisons 2.change fat to CH 2 O (glyoxysomes) 3.Detoxify & recycle photorespiration products

Peroxisomes Fn: 1.destroy H 2 O 2, other O 2 -related poisons 2.change fat to CH 2 O (glyoxysomes) 3.Detoxify & recycle photorespiration products 4.Destroy EtOH (made in anaerobic roots)

Peroxisomes ER can make peroxisomes under special circumstances! e.g. peroxisome-less mutants can restore peroxisomes when the wild-type gene is restored

endosymbionts 1) Peroxisomes (microbodies) 2) Mitochondria

Mitochondria Bounded by 2 membranes

Mitochondria 2 membranes Smooth OM

Mitochondria 2 membranes Smooth OM IM folds into cristae

Mitochondria -> 4 compartments 1) OM 2) intermembrane space 3) IM 4) matrix

Mitochondria matrix contains DNA, RNA and ribosomes

Mitochondria matrix contains DNA, RNA and ribosomes Genomes vary from 100,000 to 2,500,000 bp, but only genes

Mitochondria matrix contains DNA, RNA and ribosomes Genomes vary from 100,000 to 2,500,000 bp, but only genes Reproduce by fission

Mitochondria matrix contains DNA, RNA and ribosomes Genomes vary from 100,000 to 2,500,000 bp, but only genes Reproduce by fission IM is 25% cardiolipin, a bacterial phospholipid

Mitochondria Genomes vary from 100,000 to 2,500,000 bp, but only genes Reproduce by fission IM is 25% cardiolipin, a bacterial phospholipid Genes most related to Rhodobacteria

Mitochondria Fn : cellular respiration -> oxidizing food & supplying energy to cell Also make many important biochemicals

Mitochondria Fn : cellular respiration -> oxidizing food & supplying energy to cell Also make important biochemicals & help recycle PR products

endosymbionts 1)Peroxisomes 2)Mitochondria 3) Plastids

Plastids Chloroplasts do photosynthesis Amyloplasts store starch Chromoplasts store pigments Leucoplasts are found in roots

Chloroplasts Bounded by 2 membranes 1) outer envelope 2) inner envelope

Chloroplasts Interior = stroma Contains thylakoids membranes where light rxns of photosynthesis occur mainly galactolipids

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

Chloroplasts Contain DNA, RNA, ribosomes 120, ,000 bp, ~ 100 genes

Chloroplasts Contain DNA, RNA, ribosomes 120, ,000 bp, ~ 100 genes Closest relatives = cyanobacteria

Chloroplasts Contain DNA, RNA, ribosomes 120, ,000 bp, ~ 100 genes Closest relatives = cyanobacteria Divide by fission

Chloroplasts Contain DNA, RNA, ribosomes 120, ,000 bp, ~ 100 genes Closest relatives = cyanobacteria Divide by fission Fns: Photosynthesis

Chloroplasts Fns: Photosynthesis & starch synth Photoassimilation of N & S

Chloroplasts Fns: Photosynthesis & starch synth Photoassimilation of N & S Fatty acid & some lipid synth

Chloroplasts Fns: Photosynthesis & starch synth Photoassimilation of N & S Fatty acid & some lipid synth Synth of ABA, GA, many other biochem

Chloroplasts & Mitochondria Contain eubacterial DNA, RNA, ribosomes Inner membranes have bacterial lipids Divide by fission Provide best support for endosymbiosis

Endosymbiosis theory (Margulis) Archaebacteria ate eubacteria & converted them to symbionts

Endosymbiosis theory (Margulis) Archaebacteria ate eubacteria & converted them to symbionts

Endosymbiosis theory (Margulis) Archaebacteria ate eubacteria & converted them to symbionts

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

Cytoskeleton Actin fibers (microfilaments) ~7 nm diameter Form 2 chains of polar actin subunits arranged in a double helix

Actin fibers polar subunits arranged in a double helix Add to + end Fall off - end Fn = movement

Actin fibers Very conserved in evolution Fn = motility Often with myosin

Actin fibers Very conserved in evolution Fn = motility Often with myosin: responsible for cytoplasmic streaming

Actin fibers Very conserved in evolution Fn = motility Often with myosin: responsible for cytoplasmic streaming, Pollen tube growth & movement through plasmodesmata

Actin fibers Often with myosin: responsible for cytoplasmic streaming, Pollen tube growth & movement through plasmodesmata

Intermediate filaments Protein fibers 8-12 nm dia (between MFs & MTs) form similar looking filaments Conserved central, rod-shaped  -helical domain

Intermediate filaments 2 monomers form dimers with parallel subunits Dimers form tetramers aligned in opposite orientations & staggered

Intermediate filaments 2 monomers form dimers with parallel subunits Dimers form tetramers Tetramers form IF

Intermediate filaments 2 monomers form dimers with parallel subunits Dimers form tetramers Tetramers form IF Plants have several: Fn unclear

Microtubules Hollow, cylindrical; found in most eukaryotes outer diameter - 24 nm wall thickness - ~ 5 nm Made of 13 longitudinal rows of protofilaments

Microtubules Made of  tubulin subunits polymerize to form protofilaments (PF) PF form sheets Sheets form microtubules

Microtubules Protofilaments are polar  - end  + end all in single MT have same polarity

Microtubules In constant flux polymerizing & depolymerizing Add to  (+) Fall off  (-)

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

Microtubules Control growth by controlling rates of assembly & disassembly Are constantly rearranging inside plant cells!

Microtubules Control growth by controlling rates of assembly & disassembly Are constantly rearranging inside plant cells! during mitosis & cytokinesis

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

µT Assembly µTs always emerge from Microtubule-Organizing Centers (MTOC)

µT Assembly µTs always emerge from Microtubule-Organizing Centers (MTOC) patches of material at outer nuclear envelope

Microtubules MAPs (Microtubule Associated Proteins) may: stabilize  tubules alter rates of assembly/disassembly crosslink adjacent  tubules link cargo

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

µT functions 1)Give cells shape by guiding cellulose synth

µT functions 1)Give cells shape by guiding cellulose synth 2)Anchor organelles

µT functions 1)Give cells shape by guiding cellulose synth 2)Anchor organelles 3)Intracellular motility