what is the difference in lipid and protein composition between membranes determined by?
957859
Their function in the body. For instance, cells that require a lot of communication between them and the outside have a lot of transmembrane proteins that others that are more "isolated".
733284
Cell membranes and cytoplasm are structures of all cells--both prokaryotic and eukaryotic.  Prokaryotic cells do not have any of the membrane-bound organelles, such as a nucleus, Golgi body, endoplasmic reticulum, etc.
829422
Yes, lipoproteins and cholesterol do limit a membrane's permeability - but it's also important to note that they are there for a reason.  Molecules like cholesterol also add to the fluid mosaic model and actually make molecules more fluid in colder temperatures by pushing around the bilipid layer.
1163963
Do you mean the molecular composition or macroscopic composition? There would be too much to post here so I suggest you visit the following\n\nhttp://users.rcn.com/jkimball.ma.ultranet/BiologyPages/B/Blood.html#formation
926065
Transport is a more general term.\nTransport proteins can be carriers or channels.\nCarriers bind the small molecule that is going to be transported and flip from one side of the membrane to the other. or change their shape so that the molecule binds while being on one side of the membrane and is released on the other.\nChannel proteins, as the name indicates, create tunnels in the membrane through which molecules can pass. The size of the opening and some additionals things make the channels specific to certain molecules. Also the channels can open and close according to the cell's needs.
581495
Just go to yahoo and type:\nlipids lumen intestine\n\nhttp://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/smallgut/absorb_lipids.html\n\n"recently, a specific transport protein has been identified that ferries cholesterol from the intestinal lumen into the enterocyte. From there, cholesterol is incorporated into chylomicrons and shuttled into blood by the mechanisms described above."
1069778
All fats are lipids, but not all lipids are fats. There are oils and waxes such as the oil on your skin or the wax on a cucumber. Fat is normally a lipid that is solid at room temperature, whereas an oil is liquid.
116741
Lipid soluble molecules diffuse through membrane lipids. Small soluble molecules and ions diffuse through membrane channels.
872390
ions are polar, so they don't mix with the non-polar lipid bilayer. there are protein channels for their transportation, and pumps and all that..
290719
It appears that one side of the phospholipid is attracted to the water, while the other side is repelled by the water.\n\n"Amphipathic phospholipids will form an artificial membrane on the surface of water with only the hydrophilic heads immersed in water (Langmuir, 1917). \n\nAmphipathic = Condition where a molecule has both a hydrophilic region and a hydrophobic region. \n\nDeduction: Because of their molecular structure, phospholipids can form membranes."
416430
There are various means of determining this, and without any specific data on what elements are involved in the answer you are looking for, the link below is the best reference I can find that can answer this question in a mostly generalized way.
567411
Usually receptors are glycolipids that occur on the surface of a membrane.  The lipid part is part of the membrane, while the glyco- part is the specific receptor.
752240
proteins-amino acids, nucleic acids-nucleotides, carbohydrates (sugars)-glucose, and lipids-gylcerol and fatty acids
695871
it has phospholipids that have two polls one hydrophobic and the other hydrophylic. That's how it connects the lipids with H2O.\nHope this helps :)
837454
Cholesterol is an important component of cell membranes embedded in the hydrophobic areas of the inner region. It is required to control the fluidity of cell membranes. On the one hand, cholesterol breaks up close packing of the phospholipid tails and makes the membrane more fluid. On the other hand, the effect of cholesterol is to reduce leakage of water and ions through the lipid bilayer, probably by reducing the sideways motion of the lipid molecules. Thus, cholesterol regulates the fluidity of the plasma membrane, preventing it from becoming either too rigid or too fluid.
613788
The endomembrane system is the system of internal membranes within eukaryotic cells that divide the cell into functional and structural compartments, or organelles. Prokaryotes do not have an endomembrane system and thus lack most organelles.\n\nThe endomembrane system also provides a transport system, for moving molecules through the interior of the cell, as well as interactive surfaces for lipid and protein synthesis. The membranes that make up the endomembrane system are made of a lipid bilayer, with proteins attached to either side or traversing them.\n\nThe following organelles are part of the endomembrane system:\n\n    * The plasma membrane is a phospholipid bilayer membrane that separates the cell from its environment and regulates the transport of molecules and signals into and out of the cell.\n    * The nuclear envelope is the membrane around the nucleus of the cell.\n    * The endoplasmic reticulum is a synthesis and transport organelle [the endoplasmic reticulum is an extension of the nuclear envelope].\n    * The Golgi apparatus acts as the packaging and delivery system for molecules.\n    * Lysosomes are the "digestive" units of the cell. They utilize enzymes to break down macromolecules and also act as a waste disposal system.\n    * Vacuoles act as storage units in some cells.\n    * Vesicles are small membrane-enclosed transport units that can transfer molecules between different compartments.
771971
Cell membrane, or phospholipid bi-layer.