Question

Would you expect the properties of the luminal side of Golgi membranes to be more similar to the extracellular or cytosolic side of the plasma membrane? Why?

Answer 1

Golgi membranes are the organelles responsible for the post processing of protiens and other macro molecules. Since it is a membrane it contanes two sides the outer or cytosolic face and inner or luminal face. Generaly cytosolic is reductive in nature meaning that there are molecules which are ready to supply electrons and the luminal region is generally oxidative.

The luminal side of the golgi membrane will be similar to that of the extracellular or expolasmic phase since the membranes follow a rule called "conservation of membrane topology" which states the the bound surface/ the exposed surface should always face the same environment.

in the figure the skyblue represent the exoplasmic face and darkblue the endoplasmic/cytosolic of the plasma membrane. the golgi external surface is exposed to the cytosolic part of plasma membrane so according to the law to conserve the topology while bud formation or fusion the, golgi external part should face the cytosolic part of plasma membrane. hence the luminal face should face the external surface that is the exoplasmic phase of plasma membrane.