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2011-11-16 13:14:00

exam 3
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  1. What are the two difference between stems and leafs
    • 1. Stems are radially symmetrical
    • 2. Stems are indeterminate
  2. What are the two surfaces of leaves and which side are they one?
    • 1. adaxial-top surface
    • 2. abaxial-bottom surface
  3. What are the 3 axis leafs can be divided into?
    • 1. Proximodital-form base of leaf to tip
    • 2. Adaxial/Abaxial-top to bottom
    • 3. Centrolateral-from center of leaf to edge
  4. Plastochron
    time interval b/t the intitation of 2 successive leaf primordia
  5. Spiral phyllotaxis
    inititation of leaves with an angle between them of 137.5
  6. What are the 3 steps in leaf intiation?
    • 1. specifying of leaf founder cells in PZ
    • 2. outgrowth of cell to form a bulge
    • 3. morphogensis w/in leaf primodia to establish flat structure
  7. T/F: existing leaf primordia prevent new leaf initiation at postions immediatly adjacent to them
  8. Is Auxin required for leaf initation?
  9. Which side of leaf primordia is adjacent to the meristem?
  10. Which side of the leaf primordia points away from the meristem
  11. Which side of the leaf do axillary meristems arise?
  12. The polarity of adaxial-abaxial primordia involves a signal from where?
    The SAM
  13. phan
    radialized leaves; loss of vascular polarity; loss of adaxial epidermis and palisade mesophyll(abaxial leaves)
  14. phb-ld
    radialized leaves; loss of abaxial cell types(adaxial leaves)
  15. What two genes are the primary determinate of leaf polarity?
    • 1. KAN for abaxial
    • 2. PHB, PHV, REV for adaxial
  16. KAN
    responsible for abaxial polarity
  17. PHB, PHV, REV
    responsible for adaxial polarity
  18. What are the 3 memebers of the KAN family, and which act partially redundant?
    • KAN1, KAN2, KAN3
    • kan1, kan2 double mutants
  19. kan1kan2 double mutants
    partially adaxial, reduced lamina expansion, floral organs adaxial
  20. 35S:KAN1
    results in transformation of adaxial cell to abaxial cells, thin pointed cotelydons; lack of SAM and vascular tissue in the hypocotyl
  21. III HD-ZIP gene family
  22. phb-1d and phv-1d
    radialized and adoxail leaves; loss of abaxial cell types and radialized leaves
  23. rev phb phv
    seedlings has a single radialized and abaxialized cotlyedons and lack SAM
  24. Describe the class III HD-ZIP proteins
    Transcription factor which is divided into three domains: homedomain, leucine zipperm and sterol/lipid binding domain(START)
  25. What does KAN repress
    PHB like gene expression in the abaxial domain
  26. What doe PHB/PHV/REV repress?
    KAN gene expression in the abaxial domain
  27. Signal from meristem____ PHB/PHV/REV___KAN__abaxial fate
    ----> , -----I ------->
  28. PHB-like genes are regulated by what RNA
  29. What are the two miRNAs
    miR165 and miR166
  30. What is the binding site for the miRNAs
    START domain within the PHB mRNA
  31. Which domain is the mRNA expressed in?
  32. How does the miRNA work?
    it restricts the the expression of PHB in the adaxial domain
  33. How does phb-1d mutants act in relation to miRNA
    miRNA is not able to bind so PHB is not cleaved is expresssed thru out leaf primordia
  34. What type of signals determine whetther the VM turns into IM
    both internal and external signals
  35. What are the 2 external siganls that determine the switch from VM to IM?
    • Photoperiod
    • temperature
  36. Photoperiod
    daily recurring patter of light and dark periods
  37. What are the 3 types of photoperiodism?
    • 1. Day-neutral
    • 2. Short-day
    • 3. Long-day
  38. Short-day plants
    require short days and long nights
  39. Long-day plants
    require lond days and short nights
  40. Obligate
    require either a short day or long night
  41. Facultative
    cant flower even if it does not have a short day/long day
  42. Bunning Model
    photoperiodic responses occur based on temperal co-occurance of an internal clock-regulated protein. in long day protein promotes flowers in short days regulator is a repressor of flowering
  43. Florigen
    flower hormone that is expressed in the leaves and moves thru the phloem to the SAM which is promoted by CO
  44. What does CO promote
  45. What are the four pathways that control flowering in arabidopsis
    • 1. photoperiodic=promotes in long days
    • 2. autonomous= promoted by internal development signal
    • 3. vernalization=promoted by exposure to cold
    • 4. GA=promotes bu gibberillins
  46. What do CO mutants do in realtion to flowering in long day
    delays it