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Pradžia>Biologija>Transport of Substances across the Plasma Membrane in Eukaryotic Cells

Transport of Substances across the Plasma Membrane in Eukaryotic Cells


Darbas anglų kalba. Structure. Phospholipids Bilayer. Transmembrane Proteins. Glycoproteins and Glycolipids. Membrane Cholesterol. Transport across membranes. Diffusion. Osmosis. Active Transport. Endo-/Exocytosis.


These have a head and a tail, each with different properties. The head is polar and so will mix with water readily (Hydrophilic) and the tail is non-polar and so repels water (Hydrophobic). In the water environment of living cell, these form a two layered structure call the phospholipids bilayer, where all the tails point towards each other and the heads point out into the watery environment surrounding the cell.
Phospholipids are made of a glycerol molecule joined to two fatty acids and a phosphate group. The phospholipids bilayer forms a very effective barrier for water soluble molecules because of the presence of the hydrophobic tails it also stops the movement of charged ions and molecules, because of the polar head.
Transmembrane proteins embedded in the plasma membrane play a very important role in the transport of substances into and out of the cell. The proteins are embedded either in the outer layer, inner layer or across the whole membrane (phospholipids bilayer). The membranes which span the across the whole membrane often have hydrophilic channels through them, to allow the movement of water soluble molecules such as glucose.
These are made of short branching carbohydrate chains attached to proteins and lipids in the membrane. They give other functions to the membrane. For example they allow the proteins to act as receptors that would detect chemical molecules such as hormones and trigger an action within the cell.
The amount of cholesterol differs between types of plasma membranes. Bacteria for example do not have any cholesterol in their plasma membranes. The presence of cholesterol has few but very important functions in the plasma membrane of eukaryotic cells. The cholesterol immobilizes the first few hydrocarbons of the phospholipid molecules; this makes the lipid bilayer less deformable and decreases its permeability to small water soluble molecules. Without cholesterol a eukaryotic cell would need a cell wall (similar to bacteria). ...

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Tinklalapyje paskelbta2006-03-24
DalykasBiologijos referatas
Apimtis9 puslapiai 
Literatūros šaltiniai17
KalbaAnglų kalba
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Viso autoriaus darbų3 darbai
Metai2006 m
Švietimo institucijaLietuvos sveikatos mokslų universitetas
Failo pavadinimasMicrosoft Word Transport of Substances across the Plasma Membrane in Eukaryotic Cells [speros.lt].doc




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  • Referatai
  • 9 puslapiai 
  • Lietuvos sveikatos mokslų universitetas / 1 Klasė/kursas
  • 2006 m
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