Unity Across Plants Flashcards
Primary cell wall
Secondary cell walls
Several deposits of lignin and much stronger since it is several um thick
How much of the cell space does the vacuole take up?
80-90%
How many chloroplasts per cell?
20-40 (5-8um long)
Peroxisomes
Spherical organelles that function to oxidize compounds, and also to break down peroxide, a by-product of cellular reactions
Plasmodesmata
Tubular extensions of plasma membrane 40-50nm in diameter that transverse the cell wall and connect two cells. ER also bridges the cells. Compounds which are around 2nm in diameter may be transported through the microchannels formed by the plasma membrane and ER in the cavity.
Symplast
Continuous path through cells by cytoplasm
Apoplast
Outside protoplasts and chloroplasts functioning as a second continuous space
Plant cell mitochondria
Site of respiration; usually 3um long
Dermal tissues
Epidermis, cuticle, guard cells, root hairs
Ground tissues
Parenchyma, collenchyma, sclerenchyma
Parenchyma
Thin-walled, metabolically active cells, functional in metabolism, photosynthesis
Collenchyma
Narrow, elongated cells with thick primary walls, provide structural support to growing plant body; stretch as organs grow
Sclerenchyma
Consists of two types of cells:
Sclereids, which range from spherical to branched, widely distributed throughout the plant
Fibers, which are narrow, elongated cells commonly associated with vascular tissues
Both have thick secondary walls, are dead at maturity, and provide mechanical support to non-elongating parts of plant
Vascular tissue
Xylem–carries water and nutrients
Tracheids in gymnosperms, vessels in angiosperms
Phloem–carries sugars and signal molecules
Sieve cells in gymnosperms, sieve tubes in angiosperms
How many different species of angiosperm and gymnosperm?
Angiosperms–250,000
Gymnosperms–700
What are 5 characters that define a good model plant?
Grows and germinates quickly Easily observable Genome can be easily manipulated Beneficial to science, costs are low Gives off many progeny
Apoplast and Symplast:
Which is better suited to transport water?
Which for large biomolecules?
Apoplast is better for conducting water through areas not cluttered with organelles
Symplast is better for conducting large biomolecules through cytoplasm
What makes up most of the mass of plant cells?
Water
Why do plants need so much water?
Plants need to open stomata to access CO2, but most water will transpire within an hour after uptake
What can transpiration also do?
Passive cooling
Why is water a good choice of molecule for plants?
Hydrogen bonds, supersolvent, high specific heat, high surface tension for ease of capillary action, high tensile strength
Diffusion
Driving force is concentration gradient (delta c/ delta x)
Transport coefficient is diffusion coefficient D
FICK’S LAW: Flow = -D x (delta c/ delta x)
Time to diffuse = L^2 / D
Bulk flow
Driving force in bulk flow is pressure gradient (pressure pot. / change in x)
Transport coefficient in bulk flow is hydraulic conductance (Kh)
DARCY’S LAW: Flow = Kh x (pressure pot. / change in x)
POISEUILLE’S LAW: Kh = pi x r^4 / (8 x viscosity of liquid (n))
