1.
1. Understanding the roles of cell membrane & their importance to all life-forms (
Definition, Types, Nature, Composition, Structure, Role in life, Function)
Define CellMembrane :
The delicate membrane that forms the outer surface of the protoplasm of a cell & balance the
passage of materials inside & outside of the cell. It is made up of proteins,
lipids & often incorporates molecular receptors.
Types Of Cell Membrane:
There are three main types of cell membrane according to the transportation.
a) Passive transport
 Passive diffusion
 Facilitated diffusion
a) Active transport
b) Vesicular transport
 Endocytosis
 Exocytosis
a) Passive transport
Transportation is commonly the
traveling of ions & other atomic
or molecular elements in all cell
membranes without the need for
energy input. Unlike active
circulation, it does not require
cellular input because it is driven
by the tendency of the growth
system to entropy.
 Passive diffusion
Passive diffusion is an
important process for the
absorption of many drugs, their
transfer to the tissues, & their
regeneration from the renal
tract into the bloodstream
during renal bleeding.
 The cell membrane gives permission a
unicellular organism to move.

2.
 Facilitated diffusion
Facilitated is the process of the automatic
transport of molecules or ions through the
body's natural membrane by trans
membrane interacting proteins.
b) Active transport
In cell biology, active transport travels
through molecules across the membrane from
the region of low concentration to the region of
high concentration - as opposed to the
concentration gradient. Active mobility
requires the power of the cell to accomplish
this movement. It needs ATP.
c) Vesicular transport
Vesicular mobility is a very important
mechanism for the exchange of proteins &
lipids between membrane-bound
organelles in eukaryotic cells.
Vesicles are formed by budding off from
the cell membrane or from the membrane
organelles of the cell.
 Endocytosis
Endocytosis is a cellular process in which
substances are delivered to a cell. The
material to be enclosed is surrounded by
the location of the cell membrane, which
explodes inside the cell & around the
vesicle containing the material.
Endocytosis involves pinocytosis &
phagocytosis.

3.
 Exocytosis
Exocytosis is an active & mass transport
system in which a cell releases cells into a
cell by releasing them through a process
that supports energy.
Nature Of Cell Membrane:
It is a semi-permeable membrane. It gives permission only choosy material to pass through it. Cell
membranes are composed primarily of phospholipids in the form of a bilayer interspersed with
(CH2O)n and protein groups.
Composition Of Cell Membrane:
1. Phospholipids
2. Cholesterol
3. Proteins
 Integral
 Peripheral
1.Phospholipids
Phospholipids are a class of lipids that form
a major part of all cell organs. They can form
lipid by layers because of their water-loving
character. The composition of the
phospholipid molecule usually consists of
two "tails" of hydrophobic acid & a water-
loving "head" containing the phosphate
group.

4.
2.Cholesterol
 Cholesterol is an organic molecule.
Cholesterol is biosynthesized by all animal
cells & is fundamental structural component
of animal cell membranes. It is a sterol, a
type of lipid.
3.Proteins
Proteins are building blocks of
amino acid.
 Integral
It is embedded in the cell
membrane /plasma
membrane.
 Peripheral
It interact with the surface of the
lipid bilayer of cell membranes.
Unlike
integral proteins, peripheral
proteins do not enter into the
hydrophobic space within the
cell membrane.
Structure Of Cell Membrane:

5.
Membranes consist of a Phospholipid bilayer mingled with a variety of proteins in a fluid mosaic
manner. The surface of cell membranes are water-loving the interior are hydrophobic..
Role in life of Cell Membrane :
 They contain receptors & channels that gives permission to specific molecules, nutrients,
wastes, such as ions, & metabolic products, that mediate cellular & extracellular
activities.
 They keep poisonous substances out of the cell.
Function Of cell membrane:
 Maintains the physical integrity of the cell.
 Contains receptor which recognize & respond to specific signals.
 The molecule of gasses can pass easily through it.
 It protects the cell from its surroundings.
 It gives –ve charge to cell & repel to other particles.
 It helps in communication & recognition.