Translocation

Translocation  Transport of soluble food material from one plant to another via phloem or 

xylem.

Phloem transports carbohydrates that are non-reducing sugars as reducing sugars like glucose are too chemically reactive to be transported.

Most common transported sugar is sucrose (table sugar) that is made up from glucose and fructose.

Translocation

Phloem transports sugars from a “source” to a “sink”

Source - Exporting Regions that produces sugar beyond their needs.

Sink – Any area that does not produce any or enough sugar.

Phloem transports sugars from a “source” to a “sink”

Phloem cells are connected by

Pierced structures that creates a direct connection between cytoplasm of connected phloem cells.

Translocation is accomplished by a

process called phloem

loading and unloading.

Phloem Loading Leads to buildup of sugars causing the

phloem cells to be hypertonic/ higher osmotic pressure (pressure that can be build in a space that is permeable to a solvent).

Causing water to enter sieve elements from xylem through osmosis.

Thus, phloem osmotic pressure increases.

In Sink Tissues Phloem unloading leads to lower

sugar concentration causing phloem cells to be hypertonic.

Water leaves phloem and enters sink sieve elements and xylem via osmosis.

Thus, phloem osmotic pressure decreases.

Phloem solution moves along a gradient of

pressure generated by a solute concentration

difference between source and sinks end pathways.

At source end of pathway

There is an active transportation of

sugars into sieve cells then water flows into sieve cells and thus

osmotic pressure increases.

At sink end of pathway

There is an unloading of sugars then water flows out of the sieve cells and thus osmotic pressure decreases.

The End :D

Done By: Jerry, Rafiqah, Hui Zhen, Benjamin