Parts of the cell membrane

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  • Created on: 13-12-11 19:12
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The many Parts of the Cell Membrane
Protein Channels & Carrier Proteins
A watery pathway through the interstices of a protein molecule by
which ions and small molecules can cross a membrane into or out of a
cell by diffusion. A channel protein can act as just a tunnel for all
molecules below a certain size, or specifically select an exact molecule
and actively force it through the membrane in only one direction, or
anything in between. The cell can control its membrane traffic my
making more channel proteins of a specific type, or removing them
from the membrane to be recycled for parts.
Carrier proteins are proteins involved in the movement of ions, small
molecules, or macromolecules, such as another protein, across a
biological membrane. Carrier proteins are integral membrane proteins;
that is they exist within and span the membrane across which they
transport substances. The proteins may assist in the movement of
substances by facilitated diffusion or active transport.
Carbohydrate Chain
The most important function they do is serve as 'recognition' markers. This is the major way in which
your body's immunity will recognize 'self' from 'non-self' and know when appropriate times are to
mount an immune response. It is often in the form of oligosaccharides (3- 10 sugar molecules) . it is
attached to integral or peripheral proteins or to lipids forming the cell membrane. it is acting as cell
marker, helps in cell - cell interaction, guiding the hormones to its receptor. it is seen only in the outer
aspect of cell membrane and you cannot find it on the
cytoplasm side of cell membrane.
A molecule that consists of a carbohydrate plus a protein.
Glycoprotein's play essential roles in the body. For
instance, in the immune system almost all of the key
molecules involved in the immune response are
Hydrophilic Channel
Hydrophilic channels are there to allow water soluble molecules to diffuse in and out of the cell when
needed. Many of the membrane-associated proteins have hydrophilic and hydrophobic regions. The
hydrophilic regions are used to help anchor the protein inside of the cell membrane. Some proteins
extend across the lipid bilayer, others cross the bilayer several times

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Cell Surface Receptors
Cell surface receptors are specialized integral membrane proteins that take part in communication
between the cell and the outside world. Extracellular signalling molecules (usually hormones,
neurotransmitters, growth factors or cell recognition molecules) attach to the receptor, triggering
changes in the function of the cell. The binding initiates a chemical change on the intracellular side of
the membrane.…read more


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