Biology Forums - Study Force

can you explan to me the uploading and unloading inside the leaves , especially in the phloem plz ?

Thank me later :) View these two and I guarantee you'll understand. If not, reply back to me and I will explain it!

FIRST VIEW THIS ANIMATION: (Bottom Link)

http://glencoe.mcgraw-hill.com/sites/9834092339/student_view0/chapter38/animation_-_phloem_loading.html (http://glencoe.mcgraw-hill.com/sites/9834092339/student_view0/chapter38/animation_-_phloem_loading.html)

Biology: Phloem: The Movement of Sap (http://www.youtube.com/watch?v=zznV9TIF9AU#)

Here is an image of Loading (Attached)

Loading process at ‘source’ tissues / organs involves several steps:

1. Triose phosphates formed in Calvin Cycle move from chloroplast to cytosol where sucrose synthesis occurs (day) or stored starch is converted to maltose in chloroplast and exported to cytosol for sucrose synthesis (night)
2. Sucrose moves from producing cells in mesophyll to cells in vicinity of sieve cells in smallest leaf veins (= short-distance transport)
3. Sugars transported into companion cells and sieve tube elements – sugars become concentrated through   apoplastic loading  or  symplastic  loading
4. Once loaded into phloem – sugars (and solutes) are translocated from source to sink (= export using long-distance transport)