Re: What is the difference in permeability between cell wall and cell membrane?

DIFFERENCE IN PERMEABILITY BETWEEN CELL WALL AND CELL MEMBRANE

Cell wall is a rigid layer located external to the cell membrane in the
cell. It provides the cell with structural support, protection, and acts as
a filtering mechanism. The cell wall also prevents over-expansion when
water enters the cell. Found in algae, archaea, bacteria, fungi and plants.
Most of the protests and animal cells lack cell walls. In multicellular
organisms, it permits the organism to build and hold its shape. The cell
wall limits the entry of large molecules that may be toxic to the cell. It
further permits the creation of a stable osmotic environment by preventing
osmotic lysis and helping to retain water. The primary cell wall of most
plants cells is semi-permeable, and permit the passage of small molecules
and small proteins, with size exclusion estimated to be 30-60 kDa. Key
nutrients, especially water and carbon dioxide, are distributed throughout
the plant from cell wall to cell wall in apoplastic flow. The composition,
properties, and form of the cell wall may change during the cell cycle and
depend on growth conditions.

Cell membrane (also called as plasma membrane, plasmalemma or phospholipids
bilayer) is found in all cells. It contains a wide variety of biological
molecules (proteins, lipids) which helps the cells in adhesion, ion channel
conductance and cell signaling. The plasma membrane also serves as the
attachment point for both the intracellular cytoskeleton and, if present
the cell wall. The cell membrane surrounds the cytoplasm of a cell and, in
animal cells, physically separates the intracellular components from the
extracellular environment, thereby serving a function similar to that of
skin. In some bacteria, fungi and plants, an additional cell wall forms the
outermost boundary; however, the cell wall plays mostly a mechanical
support role rather than a role as a selective boundary. The cell membrane
also plays a role in anchoring the cytoskeleton to provide shape to the
cell, and in attaching to the extracellular matrix to help group cells
together in the formation of tissues. The barrier is selectively permeable
and able to regulate what enters and exits the cell, thus facilitating the
transport of materials needed for survival. The movement of substances
across the membrane can be either passive or active. The membrane also
maintains the cell potential. Specific proteins embedded in the cell
membrane can act as molecular signals that allow cells to communicate with
each other. Protein receptors are found and functions to receive signals
from both the environment and other cells. The permeability of membranes is
the ease of molecules to pass it. This depends mainly on electric charge
and on the molar mass of the molecule. Electrically-neutral and small
molecules pass the membrane easier than charged, large ones.
Source: Wikipedia


Regards,
Devendra Dusane