Dev. Bio

The flashcards below were created by user apeterson3474 on FreezingBlue Flashcards.

  1. Formation of root hairs
    Epidermis forms root hairs, trichomes (hair cells on stems and leaves), and stomata
  2. Function of root hairs
    • absorb water
    • allow bacteria to enter
    • grows in zone of differentiation from epidermal cells
  3. Hair cell precursors
    • form trichoblasts (hair precursors)
    • structurally different than atrichoblasts (non-hair epidermal cells)
    • Cortical cells provide signal--hair cells are next to 2 cortex cells whereas non-hair cells are next to only 1
  4. Glabra 2 (gl2) mutant
    all epidermal cells make root hairs

    normlly atrichoblasts produce gl2 which produce atrichoblasts

    if plant has gl2=no root hairs
  5. Trichomes-hair or leaves and stems
    • gl2 mutants-very hairy roots/no (or small) hair on leaves
    • transparent testa glubra (ttg)-same as gl2 mutants
    • Because: ttg stimulates ttg, then no gl2
    • Werewolf (wer) expressed in non hair cells (root) are required for differentiation-wer mutation=hairy roots
    • Glabral 1 (gl1)-expressed in epidermal cells of leaf and required for trichome formation
    • In root, wer, and leaf-gl1 is needed to stimulate gl2
  6. Stomata formation
    • Asymmetrical division yields guard mother cell (GMC)
    • Adjacent cells undergo asymmetric division-smaller ones close to GMC called subsidiary cells
    • GMC divides symmetrically producing guard cells
  7. Guard cells
    • Open during day/close at night
    • contain chlorophyll which causes swelling when uptaking H2O
  8. 6 Plant hormones
    • Abscisic acid
    • Auxin
    • Brassinosterioids
    • Cytokinins
    • Ethylene
    • Giberillins
  9. Abscisic acid (ABA)
    • stomata closure
    • maintenance of dormancy
    • prevents germination
  10. Auxin
    • apical dominance
    • cell elongation
    • phototropism
    • geotropism
    • fruit development
    • xylem regeneration in wound healing
    • adventitous root formation
  11. Brassinosteroids
    • cell elongation
    • cell division
    • produces steroid reductase enzyme (in humans would produce testosterone)
    • mutant would get short plant
    • overexpress would get large plant
  12. Cytokinins
    • cell division yielding shoot formation in culture
    • delay of leaf senescence
    • release of apical buds
  13. Ethylene (gas)
    • induced by auxin
    • causes fruit ripening
    • root hair growth
    • abscission
    • senescence-when plant becomes dormant in winter
  14. Gibberillins
    • cell elongation
    • floral induction
    • seed germination
  15. Atpin mutants-auxin transport
    • auxin is the oldest studied plant hormone
    • auxin weakens the cell which allows for elongation

    • aux1-transport auxin to cells
    • atpin1-transport of auxin
  16. More on auxin
    • can flow down stem or up stem
    • sunlight inhibits auxin-this explains why stem grows towards sun (cells opposite sun can elongate w/ auxin present
    • auxin in influenced by gravity--if laid on side, shoots would grow up and roots would grow down 
  17. Plants response to hormones
    • cytokinin stimulate cell division-antagonist to auxin-excess of cytokinin (from supershoot (sps)) causes very bushy plant
    • Gibberillin pormotes tall and skinny growth-"foolish seedling disease"
  18. Hormone mutants
    • Gn1 mutants-no gibberillin-short plants
    • Gai mutants-insensitive to gibberillin-short plant
    • spindly-acts like too much gibberillin-tall plant
  19. Phytoreceptors
    Red light-daylight, bottom of lake--causes phytochromes to enter nucleus, bind with a protein that binds DNA

    Far red light-moonlight,shade under tree--causes phytochromes to leave nucleus
Card Set:
Dev. Bio
2012-11-19 06:38:54
Section 13

Plants 3
Show Answers: