1. Plan C
We will pick a problem in plant biology and see where it takes us.
Phytoremediation II
Plant products
Biofuels VIII
Climate/CO2 change III
Stress responses/stress avoidance I
Improving food production
Biotechnology
Plant movements III
Plant signaling (including neurobiology)VI
Flowering?
Regeneration? Seed germination?
Bioluminescence II

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

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

4. Mitochondria
Fn : cellular respiration
-> oxidizing food & supplying energy to cell
Also make important biochems & help recycle PR prods
Have extra oxidases: burn off excess NADH or NADPH?

5. Mitochondria
Fn : cellular respiration
-> oxidize food & supply energy to cell
Also make important biochems & help recycle PR prods
Have extra oxidases: burn off excess NADH or NADPH?
Do lots of extra biochemistry

6. endosymbionts
Peroxisomes
Mitochondria
3) Plastids

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

22. 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

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

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

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

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

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

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

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

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

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

32. Intermediate filaments
2 monomers form dimers with parallel subunits
Dimers form
tetramers
Tetramers
form IF
Plants have several
keratins: fn unclear

33. Intermediate filaments
2 monomers form dimers with parallel subunits
Dimers form tetramers
Tetramers form IF
Plants have several keratins: fn unclear
No nuclear lamins!
Have analogs that form similar structures

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

35. Microtubules
Made of ab tubulin subunits
polymerize to form protofilaments (PF)
PF form sheets
Sheets form
microtubules

36. Microtubules
Protofilaments are polar
- end
+ end
all in single MT have same polarity

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

38. 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

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

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

41. 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

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

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

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

45. 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

46. µT functions
Give cells shape by guiding cellulose synth

47. µT functions
Give cells shape by guiding cellulose synth
Anchor organelles

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