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

Plan C Pick a problem Pick some plants to study Design some experiments See where they lead us. Endomembrane system Organelles derived from the ER 1) ER 2) Golgi 3) Vacuoles 4) Plasma Membrane 5) Nuclear Envelope 6) Endosomes 7) Oleosomes. VACUOLES Vacuoles are subdivided:

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

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

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

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

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

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

  7. Peroxisomes (microbodies) 1 membrane

  8. Peroxisomes (microbodies) • found in (nearly) all eukaryotes • 1 membrane • Fn: • 1) destroy H2O2, other O2-related poisons

  9. Peroxisomes • Fn: • destroy H2O2, other O2-related poisons • change fat to CH2O (glyoxysomes)

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

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

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

  13. endosymbionts 1) Peroxisomes (microbodies) 2) Mitochondria

  14. Mitochondria • Bounded by 2 membranes

  15. Mitochondria 2 membranes Smooth OM

  16. Mitochondria 2 membranes Smooth OM IM folds into cristae

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

  18. Mitochondria • matrix contains DNA, RNA and ribosomes

  19. Mitochondria • matrix contains DNA, RNA and ribosomes • Genomes vary from 100,000 to 2,500,000 bp, but only 40-43 genes

  20. 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

  21. 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

  22. 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

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

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

  25. endosymbionts • Peroxisomes • Mitochondria • 3) Plastids

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

  27. Chloroplasts • Bounded by 2 membranes • 1) outer envelope • 2) inner envelope

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

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

  30. Chloroplasts Contain DNA, RNA, ribosomes 120,000-160,000 bp, ~ 100 genes

  31. Chloroplasts Contain DNA, RNA, ribosomes 120,000-160,000 bp, ~ 100 genes Closest relatives = cyanobacteria

  32. Chloroplasts Contain DNA, RNA, ribosomes 120,000-160,000 bp, ~ 100 genes Closest relatives = cyanobacteria Divide by fission

  33. Chloroplasts Contain DNA, RNA, ribosomes 120,000-160,000 bp, ~ 100 genes Closest relatives = cyanobacteria Divide by fission Fns: Photosynthesis

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

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

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

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

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

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

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

  41. 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

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

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

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

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

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

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

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

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

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

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