Post on 13-Dec-2015
Plan C
1.Pick a problem2.Pick some plants to study3.Design some experiments4.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, H2 (g) or electricity?
2. Climate/CO2 changeHow will plants be affected? Can we use plants to help alleviate it?
3. Stress responses/stress avoidanceStructuralBiochemical (including C3 vs C4 vs CAM)Other (dormancy, carnivory, etc)
• Plant products• Improving food production• Phytoremediation • Plant signaling (including neurobiology)• Something else?
Endomembrane systemOrganelles derived from the ER1) ER2) Golgi3) Vacuoles 4) PlasmaMembrane5) Nuclear Envelope6) Endosomes7) Oleosomes
GOLGI COMPLEXIndividual, flattened stacks of membranes made from ERFn: “post office”:collect ER products, process & deliver themAltered in each stackMakes most cell wall carbohydrates!Protein’s address isbuilt in
VACUOLESDerived from Golgi; Fns: 1)digestion
a) Organellesb) food particles
VACUOLESDerived from Golgi; Fns:1)digestion
a) Organellesb) food particles
2) storage
VACUOLESDerived from Golgi; Fns:1) digestion
a) Organellesb) food particles
2) storage3) turgor: push plasma membrane against cell wall
VACUOLESVacuoles are subdivided: lytic vacuoles are distinctfrom storage vacuoles!
Endomembrane systemOrganelles derived from the ER1) ER2) Golgi3) Vacuoles 4) PlasmaMembraneRegulates transport in/out of cell
Endomembrane systemOrganelles derived from the ER1) ER2) Golgi3) Vacuoles 4) PlasmaMembraneRegulates transport in/out of cellLipids formbarrierProteins transportobjects & info
Endomembrane System5) Nuclear envelope: regulates transport in/out of nucleusContinuous with ER
Endomembrane System5) Nuclear envelope:regulates transport in/out of nucleusContinuous with ERTransport is only through nuclear pores
Endomembrane System5) Nuclear envelope:regulates transport in/out of nucleusContinuous with ERTransport is only through nuclear poresNeed correct signal& receptor for import
Endomembrane System5) Nuclear envelope: regulates transport in/out of nucleusContinuous with ERTransport is only through nuclear poresNeed correct signal& receptor for import new one for export
Endomembrane SystemEndosomes: vesicles derived from Golgi or Plasma membraneFn: sorting materials & recycling receptors
Endomembrane SystemOleosomes: oil storage bodies derived from SERSurrounded by lipid monolayer!
Endomembrane SystemOleosomes: oil storage bodies derived from SERSurrounded 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 organelles1) Peroxisomes (microbodies)
Peroxisomes (microbodies)1 membrane
Peroxisomes (microbodies)found in (nearly) all eukaryotes1 membraneFn:
1) destroy H2O2, other O2-related poisons
PeroxisomesFn:
1. destroy H2O2, other O2-related poisons2. change fat to CH2O (glyoxysomes)
PeroxisomesFns:
1. destroy H2O2, other O2-related poisons2. change fat to CH2O (glyoxysomes)• Detoxify & recycle photorespiration products
PeroxisomesFn:
• destroy H2O2, other O2-related poisons• change fat to CH2O (glyoxysomes)• Detoxify & recycle photorespiration products• Destroy EtOH (made in anaerobic roots)
PeroxisomesER can make peroxisomes under special circumstances!e.g. peroxisome-less mutants can restore peroxisomes when
the wild-type gene is restored
endosymbionts1) Peroxisomes (microbodies)2) Mitochondria
MitochondriaBounded by 2 membranes
Mitochondria2 membranesSmooth OM
Mitochondria2 membranesSmooth OMIM folds into cristae
Mitochondria-> 4 compartments
1) OM2) intermembrane space3) IM4) matrix
Mitochondria matrix contains DNA, RNA and ribosomes
Mitochondria matrix contains DNA, RNA and ribosomesGenomes vary from 100,000 to 2,500,000 bp, but only 40-43 genes
Mitochondriamatrix contains DNA, RNA and ribosomesGenomes vary from 100,000 to 2,500,000 bp, but only 40-43 genesReproduce by fission
Mitochondriamatrix contains DNA, RNA and ribosomesGenomes vary from 100,000 to 2,500,000 bp, but only 40-43 genesReproduce by fissionIM is 25% cardiolipin, a bacterial phospholipid
MitochondriaGenomes vary from 100,000 to 2,500,000 bp, but only 40-43 genesReproduce by fissionIM is 25% cardiolipin, a bacterial phospholipidGenes most related to Rhodobacteria
MitochondriaFn : cellular respiration -> oxidizing food & supplying energy to cellAlso make many important biochemicals
MitochondriaFn : cellular respiration -> oxidizing food & supplying energy to cellAlso make important biochemicals & help recycle PR products
endosymbionts1) Peroxisomes2) Mitochondria 3) Plastids
PlastidsChloroplasts do photosynthesisAmyloplasts store starchChromoplasts store pigmentsLeucoplasts are found in roots
ChloroplastsBounded by 2 membranes
1) outer envelope 2) inner envelope
ChloroplastsInterior = stromaContains thylakoids• membranes where light rxns of photosynthesis occur•mainly galactolipids
ChloroplastsInterior = stromaContains thylakoids• membranes where light rxns of photosynthesis occur•mainly galactolipidsContain DNA, RNA, ribosomes
ChloroplastsContain DNA, RNA, ribosomes120,000-160,000 bp, ~ 100 genes
ChloroplastsContain DNA, RNA, ribosomes120,000-160,000 bp, ~ 100 genesClosest relatives = cyanobacteria
ChloroplastsContain DNA, RNA, ribosomes120,000-160,000 bp, ~ 100 genesClosest relatives = cyanobacteriaDivide by fission
ChloroplastsContain DNA, RNA, ribosomes120,000-160,000 bp, ~ 100 genesClosest relatives = cyanobacteriaDivide by fissionFns: Photosynthesis
ChloroplastsFns: Photosynthesis & starch synthPhotoassimilation of N & S
ChloroplastsFns: Photosynthesis & starch synthPhotoassimilation of N & SFatty acid & some lipid synth
ChloroplastsFns: Photosynthesis & starch synthPhotoassimilation of N & SFatty acid & some lipid synthSynth of ABA, GA, many other biochem
Chloroplasts & MitochondriaContain eubacterial DNA, RNA, ribosomesInner membranes have bacterial lipidsDivide by fissionProvide best support for endosymbiosis
Endosymbiosis theory (Margulis)Archaebacteria ate eubacteria & converted them to symbionts
Endosymbiosis theory (Margulis)Archaebacteria ate eubacteria & converted themto 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 formationleft intact by detergents that extract rest of cell
CytoskeletonActin fibers (microfilaments)~7 nm diameterForm 2 chains of polar actin subunits arranged in a double helix
Actin fiberspolar subunits arranged in a double helix• Add to + end• Fall off - end• Fn = movement
Actin fibersVery conserved in evolutionFn = motilityOften with myosin
Actin fibersVery conserved in evolutionFn = motilityOften with myosin: responsible for cytoplasmic streaming
Actin fibersVery conserved in evolutionFn = motilityOften with myosin: responsible for cytoplasmic streaming,Pollen tube growth & movement through plasmodesmata
Actin fibersOften 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 filaments2 monomers form dimers with parallel subunitsDimers form tetramersaligned in opposite orientations& staggered
Intermediate filaments2 monomers form dimers with parallel subunitsDimers form tetramersTetramers form IF
Intermediate filaments2 monomers form dimers with parallel subunitsDimers form tetramersTetramers form IFPlants have several:Fn unclear
MicrotubulesHollow, cylindrical; found in most eukaryotes
outer diameter - 24 nmwall thickness - ~ 5 nmMade of 13 longitudinal rows of protofilaments
MicrotubulesMade of tubulin subunits polymerize to form protofilaments (PF)PF form sheetsSheets form microtubules
MicrotubulesProtofilaments are polar -tubulin @ - end-tubulin @ + endall in single MT have same polarity
MicrotubulesIn constant fluxpolymerizing & depolymerizingAdd to (+)Fall off (-)
MicrotubulesControl growth by controllingrates of assembly & disassembly
because these are distinct processes can be controlled independently!
Colchicine makes MTs disassemble
Taxol prevents disassembly
MicrotubulesControl growth by controlling rates of assembly & disassemblyAre constantly rearranging inside plant cells!
MicrotubulesControl growth by controlling rates of assembly & disassemblyAre constantly rearranging inside plant cells!
• during mitosis & cytokinesis
MicrotubulesControl growth by controlling rates of assembly & disassemblyAre 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
MicrotubulesMAPs (Microtubule Associated Proteins) may:
• stabilize tubules• alter rates of assembly/disassembly• crosslink adjacent tubules • link cargo
2 classes of molecular motors1) Kinesins move cargo to µT plus end2) Dyneins move cargo to minus end “Walk” hand-over-hand towards chosen end
µT functions1) Give cells shape by guiding cellulose synth
µT functions1) Give cells shape by guiding cellulose synth2) Anchor organelles
µT functions1) Give cells shape by guiding cellulose synth2) Anchor organelles3) Intracellular motility