the waste products and take the nutrients and other products into
the cell. This task is carried out by the cell membrane. However
this is quite a hard task.
The cell membrane is a layer consisting of lipid molecules.
On the fat particles in the cell membrane, there exist some gates
ensuring the entrance into and exit from the cell and receptors
which enable the cell to recognize the external environment.
These gates and receptors are made up of lipid molecules.
The cell membrane;
-Controls exit from and entrance into the cell
-Establishes the intracellular communication
-Conveys the messages into the cell
-Determines the harmful organism such as microbes and bacteria.
In order for the cell to accomplish these activities,
The cell must know all the activities of the cell,
-Should have an amazing knowledge of chemistry,
-Should make a list of the necessary or surplus materials,
-Should have a memory and decision making ability to keep stocks
under control
-Should know the meaning of the intracellular messages and
-Should recognize the harmful agents for the cell.
The cell membrane distinguishes the required substances among
hundreds of chemicals and only lets them in. In order to accomplish
this the membrane uses different techniques according to the size
of the molecules.
Among the materials which pass through the membrane, there are
small molecules like electrons photons, ions and water molecules ,
medium- sized molecules such as amino-acids and glucose and large
molecules like protein and RNA.
The cell membrane lets the small molecules pass through the membrane
which the cell requires by diffusion.
Phospholipids and protein channels determine which molecules and
ions to pass in which rate and when they'll pass.
Protein Channels and Carrier Proteins
Some molecules pass through the protein channels on the cell membrane.
Some molecules, on the other hand, can only pass through by the help
of a carrier protein. Binding of protein to the molecule which will
be taken into the cell changes the shape of the protein and this
action allows the protein to pass through the cell membrane.
Each one of the proteins on these channels has a sequence of amino
acids of their own.
Some proteins carry out this action without taking energy from the
cell. However, there are special proteins for molecules, which are
carried against the ion and concentration flow. These proteins are
competent in an even harder task. Using the energy of the cell, they
meticulously carry the necessary material into the cell, against
the very ion and concentration flow. Meanwhile, no harm is given to
the protein channel, the passing material or the cell.
With the energy they receive from the cell, these special proteins
change their shapes and thus carry the materials matching their own
gates inside the cell.
Cell Membrane Vesicles
In larger molecules the cell membrane extends like an arm, encloses
the molecule and, joining its arms from two ends, takes the molecule
into the cell.
In order to take liquids into the cell, the cell membrane employs
another method: At the point where the liquid exists, the membrane
sinks in. The liquid filling in this structure is enclosed by the
cell membrane and thus the liquid remains within the cell when a
full sack is formed.
In both cases there exists a vesicle within the cell enclosed by the
membrane. For these materials to be used by the cell, they should
still pass through the membrane. Lysosome joins with the vesicle
and the digestive enzymes inside the vesicle break down the
material into particles small enough to pass through the membrane.
In some cases receptors enter the equation. The molecule binding
with the receptor is enclosed by the cell membrane and a vesicle
comes into being. Again lysosome joins with this vesicle and the
digestive enzymes break down the molecule into smaller pieces and
release them from the receptor. This way the cell membrane can reuse
the receptors .
The cell membrane also determines the waste and throws them out by
the vesicle method.
Relay of messages into the cell
There are hormones commissioned to any order from the brain. When
the hormone reaches the cell, it relays its message to the receptor
protein on the cell membrane. Accordingly the protein conveys the
message to the center. The cell acknowledges this order, makes a
decision and thus gets into action. These hormones can order the
cell to move, divide or even die.
Large hormones bind to the protein receptors. Receptors send
messenger molecules to the enzymes and organelles.
Cells recognizing each other
Cells recognize one another from the cell membrane
Hook-like extensions form on the outer side of the cell membrane
Thus, heart cells recognize other heart cells, liver cells recognize
other liver cells.
The cells hold on to each other by these hooks to form the organs.
Defense cells and the cell membrane
The membranes of the defense cells detect harmful external
materials. When necessary, the tentacles of the cell membrane
elongate to catch the bacteria and microbes. When the enemy is
caught it is absorbed by the cell.
The cell digests the enemy and the released particles are reused for
the benefit of the body.
This amazing wisdom and conscience displayed by the cell membrane
surely does not belong to the lipid particles and proteins. This
superior intelligence and wisdom belongs to the Almighty Allah. By
the inspiration of Allah, these processes are flawlessly carried out
in every cell membrane of each cell in our body.
It is Allah Who created the seven heavens and of the earth the same
number, the Command descending down through all of them, so that
you might know that Allah has power over all things and that Allah
encompasses all things in His knowledge. (Surat at-Talaq, 12)
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