Biology Questions and Answers
- Concerning permeability
what type of membrane is the
cell membrane?
The cell mempermeable membrane is a selbrane, i.e., ectivelyit allows the (^)
passage osolutes. f water and some selected
- What are the basic
constituents of the cell
membrane?
The cell memproteins and carbohybrane is formed of lipids,drates.
The membrane lipids ara special type of lipid to e phospholipiwhich one ds,
extremitythus assigning a phosphate group is boelectrical charge to thisund (^)
region of the molecule. Since
phospholipicharged extremityds have one electrically and a long neutral (^)
organic chain they can organize
themselves in molecules: the hydrophilic portiontwo layers of associated
(polar) of each layer faces outwards in
contact with water too) of the extracellular an(a polar d themolecul e
intracellular space and the hydrophobic
chains (from the water. non polar) face Because this typinwards isolatee of d
membrane is malayers it is also called de of two a bilipiphospolipid d
membrane.
Membrane proteins ardispersed in the compacte embedded and bilipid
structure. outer surface oCarbohydrates appear in thef the membrane
associated to some of those proteins
under the form of glycoproteibound to phospholipids formingns or
glycolipids. The membrane
carbohydrates form the glycocalix of the
membrane.
This description (with further
explanations) is kmosaic model about thnown as the fluide structure of the (^)
cell membrane.
- What are the respective
functions of phospholipids,
proteins and carbohydrates of
the cell membrane?
Membrane phospholipids hstructural function, they form thave a (^) e bilipid
membrane that constitutesmembrane itself. the cell
Membrane proteins havspecialized functions. Some of them aree several (^)
channels for substances to pass through
the membrane, others arand signalers of information, ote receptorshers ar (^) e
enzymes, others are cell identifiers
(cellular labels) athat participate in the adhesionnd there are still those
complexes binternal surface of the memetween cells or between thebrane and
the cytosketeleton.
Membrane carbohydrates, associated toproteins or to lipids, are found in the
outer surface othey have in general labeling functionsf the cell membrane and
for recognition of the cell by other cells
and substancesdifferentiate red blood cells in relation to (for example, they (^)
the ABO blood group system), immune
modulation sensitizationfunctions, functions, e pathogentc.
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