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About This Video ........................
In This Video Lecture You Will Learn Basic Concept Of Plasma Membrane
Plasma membrane or cell membrane is the outer most boundary of the cell. However, in most plant
are embedded in lipid layers in a mosaic manner (Fig.4.5). This discovery led to the proposal of
outer layers of protein (Fig.4.4). This, basic structure is called the unit membrane and is present in all
Fluid Mosaic Model. This model at present is the most accepted one. Cell membrane also contains
the cellular organelles. The modem technology has revealed that lipid bilayers are not sandwiched
charged pores through which movement of materials takes place, both by active and passive
The protein layers are not continuous and are not conined to the surface of the membrane but
Many biologists contributed to establish the structural organization of cell membrane. It was
proposed earlier that cell membrane is composed of lipid bilayer sandwiched between inner and
cells, it is covered by a cell wall. Cell membrane is chemically composed of lipids and proteins; 60
- 80% are proteins, while 20-40% are lipids. In addition there is a small quantity of carbohydrates.
between two protein layers.
transport.
Transport of materials is one of the vital roles it plays for the cell. It ofers a barrier between the
ions to maintain a deinite gradient. Many small gas molecules, water, glucose etc. being neutral can
is known as diferentially permeable or selectively permeable membrane. The substances which
cell contents and their environment, allowing only selective substances to pass through it, thus it
are lipid soluble cross it more easily than others, therefore, it regulates the low of materials and
which are not needed, constantly enter the cell by passive transport, others are taken up against
In many animal cells, the cell membrane helps to take in materials by infolding in the form of
The energy used for this movement is provided by ATP.
the concentration gradient (they move from the area of low concentration to the area of high
easily cross while ions, being charged particles, have some diiculty in crossing. Many substances
concentration). This uphill movement of materials requires energy and is termed as active transport.
vacuoles. This type of intake is termed as endocytosis which can be either phagocytosis (to engulf solid)
r pinocytosis (to take in liquid material). In neurons (nerve cells) the cell membrane
transmits nerve impulses from one part of the body to the other to keep coordination.
About This Channel.....................
I make these videos cause I love to draw and connect the complexity of science and medicine into art. I'm not saying. I'm 100% correct in all my videos, but I do try to obtain the information from credible sources.
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_ students in class 11, 12 or appearing for competitive medical exams ( NMDCAT ) will find it very beneficial
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