translocation Flashcards
what is translocation
transport of assimilates through a plant
what direction does translocation happen in the phloem
happens in either direction as it is bidirectional
what kind of process is translocation
an active process which requires energy
what is a source
provides assimilates to the plant from reactions or storage for transport
examples of sources in the plant
-green leaves and stems
-storage organs like root taps
-food stores in seeds
what are sinks
use assimilates from the plant in various processes
examples of sinks in plants
-growing roots
-active processes in the roots and stem
-meristem cells activity dividing
-developing stores (seeds, fruits or storage organs)
what happens in the symplast route in translocation
-assimilates are stored in the vacuoles of cells
-theyre moved through the cytoplasm of mesophyll cells into the sieve tubes across connecting plasmodesmata
-passive process
-the assimilates are moved by changes in water potential of cells
where are assimilates stored in cells
vacuole
what kind of process is the symplast route in translocation
passive process
what are assimilates moved by in translocation
by changes in water potential of cells
what happens in the apoplast route in translocation
-assimilates diffuse through the cell wall and intermembrane spaces of mesophyll cells
-energy needed for actively transport hydrogen ions out of the companion cells
-this increases conc gradient outside the cells and decreases their conc inside the companion cells
-conc gradient is created
-H+ ions diffuse back into the companion cells through cotransporter proteins. The proteins only allow movement of hydrogen ions if they’re accompanied by assimilates
how does capillary action transport water
-adhesion between the water molecules and xylem vessels takes place
-as vessels are narrow forces of attraction can pull the water up the sides of the vessel
where do assimilates diffuse in the apoplast route in translocation
through the cell wall and intermembrane spaces of the mesophyll cells
what do hydrogen ions act as in translocation
co-transporters and actively move assimilates across the membrane
what is secondary active transport
the active transport of H+ out of the cell and move assimilates against its conc gradient
-assimilates diffuse into the sieve tubes through the plasmodesmata down its concentration gradient
