Cell Membrane Structure
This membrane is composed of both proteins & lipids and the proportion of it ranges from 40:60 accordingly. The lipid content is
mainly composed of phospholipids (Lecithin, Cephalin, & Sphingomyelin) and glycolipids and sterols as well as some polysaccharides. This
composition of plasma membrane gives rigidity and stability to the cell. Apart from all these, it is also made up of fats or other triglycerides. Hence this portion of cell plays a vital role in the influx and outflux of materials through this membrane.
All the life processes take place in a cell. A cell itself is made of certain
parts. Plant and animal cells are not exactly alike. Various kinds of cells show
special differences, yet they all show some basic structural plan, which may be
expressed in the term "generalized cell". A generalized cell consists of three essential
parts: the cell membrane (plasma membrane), the cytoplasm and the nucleus.
organelles: Most parts of a cell have a definite shape, a definite
structure and a definite function. Such parts are called organelles. The organelles
have the same status in a cell as the organs have in the entire body of an animal
or plant. Cell organelles are living parts.
Cell membrane (plasma membrane or plasmalemma or phospholipid
bilayer) is present in both plant and animal cells. Each cell is surrounded by a
cell membrane. The cell membrane has fine pores through which substances may enter
or leave the cell. It is living, thin, delicate, elastic and made of proteins and
lipids (fats). Its function is to provide a mechanical barrier for the protection
of the inner cell contents and to regulate the movement of molecules in and out
of the cell. The permeability of the cell membrane is selective. The membranes that
surround the nucleus and other organelles are almost identical to the cell membrane.
Cell membrane is a lipid bilayer, which contains a wide variety of biological molecules (primarily proteins and lipids) involved in a vast array of cellular processes.
It also serves as the attachment point for both the intracellular cytoskeleton
and, if present, the cell wall. The cell wall is present only in plant cells. It is made up of a complex polysaccharide (carbohydrate) called cellulose. Its function
is to give strength and rigidity to the cell. It is non−living.