a) Liposomes are cannot be formed spontaneously but are formed when sufficient energy is available to phospholipids in polar solvent like water. b) Phospholipids when placed in water form a cluster with the hydrophilic phosphate heads facing outward in contact with the water and their hydrophobic tails extending into the cluster away from the water. Due to the proper orientation of the heads and tails in the cell membrane the fluidity is maintained and substances are allowed to move in and out of the cell. c) The transmembrane proteins function as channels and form water filled pathways through the lipid bilayer. The channels are meant for passage of selectively small ions that can pass through the diameter of the channel. Some proteins spanning the membrane act as carriers or transport molecules. These molecules help in transfer of specific substances across the membranes. Some inner membrane proteins acts as docking – marker acceptors. These proteins bind in a lock and key fashion with the docking markers of secretory vesicles. Some proteins located either in or outside of the membrane act as membrane bound enzymes regulating specific chemical reactions. Several outer surface proteins act as receptors that recognize and bind with specific signal molecules in the extra cellular environment. Some other proteins are involved in cell adhesion processes acting as cell adhesion molecules (CAMs). These molecules protrude from the outer membrane forming loops or hooks through which cells grip with one another or the connective tissue fibers grasp between the cells. Solution a) Liposomes are cannot be formed spontaneously but are formed when sufficient energy is available to phospholipids in polar solvent like water. b) Phospholipids when placed in water form a cluster with the hydrophilic phosphate heads facing outward in contact with the water and their hydrophobic tails extending into the cluster away from the water. Due to the proper orientation of the heads and tails in the cell membrane the fluidity is maintained and substances are allowed to move in and out of the cell. c) The transmembrane proteins function as channels and form water filled pathways through the lipid bilayer. The channels are meant for passage of selectively small ions that can pass through the diameter of the channel. Some proteins spanning the membrane act as carriers or transport molecules. These molecules help in transfer of specific substances across the membranes. Some inner membrane proteins acts as docking – marker acceptors. These proteins bind in a lock and key fashion with the docking markers of secretory vesicles. Some proteins located either in or outside of the membrane act as membrane bound enzymes regulating specific chemical reactions. Several outer surface proteins act as receptors that recognize and bind with specific signal molecules in the extra cellular environment. Some other proteins are involved in cell adhesion processes acting as cell adhesion mole.

1. a) Liposomes are cannot be formed spontaneously but are formed when sufficient energy is
available to phospholipids in polar solvent like water.
b) Phospholipids when placed in water form a cluster with the hydrophilic phosphate heads
facing outward in contact with the water and their hydrophobic tails extending into the cluster
away from the water. Due to the proper orientation of the heads and tails in the cell membrane
the fluidity is maintained and substances are allowed to move in and out of the cell.
c)
The transmembrane proteins function as channels and form water filled pathways through the
lipid bilayer. The channels are meant for passage of selectively small ions that can pass through
the diameter of the channel. Some proteins spanning the membrane act as carriers or transport
molecules. These molecules help in transfer of specific substances across the membranes.
Some inner membrane proteins acts as docking – marker acceptors. These proteins bind in a lock
and key fashion with the docking markers of secretory vesicles. Some proteins located either in
or outside of the membrane act as membrane bound enzymes regulating specific chemical
reactions.
Several outer surface proteins act as receptors that recognize and bind with specific signal
molecules in the extra cellular environment. Some other proteins are involved in cell adhesion
processes acting as cell adhesion molecules (CAMs). These molecules protrude from the outer
membrane forming loops or hooks through which cells grip with one another or the connective
tissue fibers grasp between the cells.
Solution
a) Liposomes are cannot be formed spontaneously but are formed when sufficient energy is
available to phospholipids in polar solvent like water.
b) Phospholipids when placed in water form a cluster with the hydrophilic phosphate heads
facing outward in contact with the water and their hydrophobic tails extending into the cluster
away from the water. Due to the proper orientation of the heads and tails in the cell membrane
the fluidity is maintained and substances are allowed to move in and out of the cell.
c)
The transmembrane proteins function as channels and form water filled pathways through the
lipid bilayer. The channels are meant for passage of selectively small ions that can pass through
the diameter of the channel. Some proteins spanning the membrane act as carriers or transport
molecules. These molecules help in transfer of specific substances across the membranes.
Some inner membrane proteins acts as docking – marker acceptors. These proteins bind in a lock

2. and key fashion with the docking markers of secretory vesicles. Some proteins located either in
or outside of the membrane act as membrane bound enzymes regulating specific chemical
reactions.
Several outer surface proteins act as receptors that recognize and bind with specific signal
molecules in the extra cellular environment. Some other proteins are involved in cell adhesion
processes acting as cell adhesion molecules (CAMs). These molecules protrude from the outer
membrane forming loops or hooks through which cells grip with one another or the connective
tissue fibers grasp between the cells.