How did Singer and Nicolson prove the Fluid Mosaic Model of a cell membrane?
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The Development of a Scientific Fact \n\nThe fluid-mosaic membrane model as a scientific fact \nWhat the model says \n\nThe fluid mosaic model of a biological membrane defines a phospholipid bilayer mixed with (integral) membrane proteins. The lipid bilayer, therefore, is not a continuous layer, but contains non-lipid molecules, in particular proteins. \n\nThe significance of the model \n\nThe fluid mosaic model is the only accepted proper description of a biological membrane. Its publication in 1972 by Singer and Nicolson (Science 1972 Feb. 18 175:23 720-31) put an end to other existing and competing models of biological membranes. These competing models assumed triple layers, with a lipid core layer and two protein layers, one on each side, but the proteins would not penetrate the lipid core, i.e., did not span the membrane. The fluid mosaic model, based on thermodynamic and functional considerations, postulated instead that proteins as the active components of signal transduction and transport,  must and can span the entire thickness of a lipid bilayer. Protein-lipid interaction was thought to be stabilized through hydrophobic (fat soluble) contact points on the surface of the proteins.  \n\nToday, the fluid-mosaic model is the only accepted model of the structure of biological membranes, including those of animals, plants, and microorganisms (see figure above for membranes of the cell wall of the bacteria Escherichia coli). the use of the same structure among all living organisms is consistent with the idea of a common ancestor organism (or organisms) from which all modern life forms have evolved. Since 1972 no modifications of the model have been necessary, also individual membranes differ in molecular composition, lipid types, or lipid to protein ratios.  \n\nTo understand the stability and form of membranes one needs to understand that they are solely determined by the aggregation behavior of phospholipids. These lipid types in effect form extensive, planar bimolecular films separating two aqueous compartments.  \n\n \n\nThe hydrophobic core of such a thin film functions as an electrical insulator (D=2; D stands for dielectric constant; a value of 2 represents hydrophobic environment, a value of 80 water) allowing diffusion of small hydrophobic solutes across membranes, but inhibits the diffusion of charged and hydrophilic, i.e., water soluble molecules. The incorporation of protein into these bimolecular films provides the necessary pathways for all charged and hydrophilic molecules. Cells have thus complete control over their membrane permeability because they can control protein function, but not the diffusion of small hydrophobic molecules across membranes. Cell membranes are thus clearly specific and selective.  \n\nTo understand the current model of biological membranes, one has to know the history of the study of cell membranes, both from a structural and functional point of view.  \n\n\nEarly developments \n\nThe first experimental indications for a bilayer structure have been obtained by measuring the size of a water surface that can be covered by phospholipids extracted from red blood cells. This area was about twice as large as the total surface area of red blood cells used to extract lipids. It turned out this first calculation was a lucky shot and with more accurate measurement, the two surface ratios would not have been 2:1 due to the presence of membrane proteins. This original finding, although not reproducible, stimulated membrane research and guided it into the right direction.  \n\nNeurobiologist started to characterize the function of neuronal cells by measuring action potentials which are the result of electrical currents flowing across cell membranes (called excitable membranes of nerve and muscle cells). Macroscopic current recordings of isolated nerve cells in the 1940s allowed the prediction of underlying molecular units called ion channels (the electric charges are carried by ions, charged atom
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http://mathworld.wolfram.com/PoincareConjecture.html
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DUE TO SURFACE TENSION POSITIVE ANGLE OF CONTACT AND INTERNAL PRESSURE.
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http://www.petrie.ucl.ac.uk/detail/Images/127/UC63502.jpg
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T1=m1*a, no matter are there m2 & m3 or not.\nT2=(m1+m2)*a, no matter whether m1 & m2 are connected with a string or are in one lump, the presence of m3 being unimportant too.
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http://www.science.uwaterloo.ca/~cchieh/cact/c120/dotstruc.html
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Mitochondria are bounded by a double membrane. \nEach of these membranes is a phospholipid bilayer with embedded proteins. \nThe outermost membrane is smooth while the inner membrane has many folds.  \nThe folds enhance the productivity of cellular respiration by increasing the available surface area. \nThe double membranes divide the mitochondrion into two distinct parts: the intermembrane space and the mitochondrial matrix. The intermembrane space is the narrow part between the two membranes while the mitochondrial matrix is the part enclosed by the innermost membrane. \nSeveral of the steps in cellular respiration occur in the matrix due to its high concentration of enzymes. \nMitochondria are semiautonomous in that they can divide and grow to make more of themselves. They also have their own DNA and ribosomes.
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2. Cell membrane and Plasma membrane.
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Maxwell's equations require that in empty space the magnetic and electric fields are divergence free: Div B=0 , Div E=0. An equivalent way of saying that, is that for any closed surface, the integral of the normal (to the surface) component of the magnetic field over the surface is zero. For an electric field the integral of the normal component of the electric field over the surface gives the total net charge enclosed (zero in empty space).\n\nThere are other fields with this property as well. The word flux ("flow") probably comes by analogy with hydrodynamics. The velocity v(x) of an incompressible irrotational fluid (water for example) is an example of a divergence free field. Div v = 0 just means that the total amount of water flowing across any closed surface is always zero (unless the surface encloses a source) because for each element of water flowing in, an equal amount must flow out. \n\nAny field with this property can be represented visually by drawing continuous lines in space such that the direction of the lines gives the direction of the field, and the magnitude is proportional to the density of lines per unit area in a plane perpendicular to their direction. That is, electric and magnetic fields are identified as directional flux densities. The actual lines have no physical existence; they're a conceptual device.\n\nEach line starts at a source (positive charge) and terminate at a sink (negative charge), or else (especially in the case of a magnetic field) must form a closed loop. This makes it possible to visualize easily the structure of a field particularly when the geometry is simple. \n\nFor example it's obvious that a point charge produces a field in the radial direction which decreases as the square of the distance from the charge since the lines of flux must radiate outward from the charge.
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the cell membrane is the outer part of the cell, its like the skin of it. it holds everything in the cell in place so it.
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ANSWER NO. 1\nOsmosis - a definition \n1. Movement of a solvent through a semipermeable membrane into a solution of higher concentration that tends to equalise the concentration on both sides of the membrane. \n2. A process of absorption or diffusion - osmotic adj. \n3. An innovative rock band from Northampton.\n\nANSWER NO. 2\nOsmosis: the movement of water molecules from an area of high concentration to an area of low concentration. \nCell membranes are completely permeable to water, therefore, the environment the cell is exposed to can have a dramatic effect on the cell. \nHypertonic Solutions: contain a high concentration of solute relative to another solution (e.g. the cell's cytoplasm). When a cell is placed in a hypertonic solution, the water diffuses out of the cell, causing the cell to shrivel. \n\nANSWER NO. 3\nA fully manageable and complete application made specialy for the paediatric (pediatric) sector.\n\nANSWER NO. 4\nOsmosis is the movement of water through a semi-permeable membrane from a region of low solute potential to a region of high solute potential (or equivalently, from a region of high solvent potential to a region of low solvent potential). The semi-permeable membrane must be permeable to the solvent, but not to the solute, resulting in a pressure gradient across the membrane. Osmosis is a natural phenomenon. However, it can be artificially opposed by increasing the pressure in the section of high solute concentration with respect to that in the low solute concentration. The force per unit area required to prevent the passage of solvent through a selectively-permeable membrane and into a solution of greater concentration is equivalent to the turgor pressure. Osmotic pressure is a colligative property, meaning that the property depends on the concentration of the solute but not on its identity. It is an important topic in biology because it provides the primary means by which water is transported into and out of cells.\n\nBasic explanation of osmosis\nConsider a permeable membrane, such as visking tubing, with apertures small enough to allow water molecules, but not larger molecules, to pass through. Suppose the membrane is in a volume of pure water. At a molecular scale, every time a water molecule hits the membrane, it has a defined likelihood of passing through. In this case, since the circumstances on both sides of the membrane are equivalent, there is no net flow of water through it. However, if there is a solution on the other side, that side will have fewer water molecules and thus fewer collisions with the membrane. This will result in a net flow of water to the side with the solution. Assuming the membrane does not break, this net flow will slow and finally stop as the pressure on the solution side becomes such that the diffusion in each direction is equal. Osmosis can also be explained via the notion of entropy, from statistical mechanics. As above, suppose a permeable membrane separates equal amounts of pure solvent and a solution. Since a solution possesses more entropy than pure solvent, the second law of thermodynamics states that solvent molecules will flow into the solution until the entropy of the combined system is maximized. Notice that, as this happens, the solvent loses entropy while the solution gains entropy. Equilibrium, hence maximum entropy, is achieved when the entropy gradient becomes zero.\n\nExamples of osmosis\nMany plant cells perform osmosis. This is because the osmotic entry of water is opposed and eventually equaled by the pressure exerted by the cell wall, creating a steady state. In fact, osmotic pressure is the main cause of support in plant leaves.\n\nWhen a plant cell is placed in a hypertonic solution, the water in the cells moves to an area higher in solute concentration, and the cell shrinks and so becomes flaccid [pron. flaxid]. (This means the cell has become plasmolysed - the cell membrane has completely left the cell wall due to lack of water pressure
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For circular membranes, the radial part of the vibrations is a bessell function while the angular part is an ordinary trigonometric function. This comes from writing the wave equation in polar coordinates and doing a separation of variables. The radial function turns out to satisfy Bessell's equation. The frequencies then turn out to correspond to the zeros of the bessell functions.
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Hi - here are some ideas without seeing your actual data.  First - the system was too hot during transfer to  the membrane - be sure you aren't running it at too high  a voltage.   Second, not an issue with the  blot,  but with  the gel  - was it expired?  not fully polymerized? were the  wells free of debris when loading  samples?   sometimes with highly concentrated samples, especially cell lysates,  this  can  happen  because  of  viscosity  in t he  sample  (from  DNA for example). good  luck.
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Using the Michaelis-Menten equation.\n\nMore details on teh attached link\n\nhttp://www.le.ac.uk/by/teach/biochemweb/tutorials/michment2print.html\n\nGood luck
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Myoelastic-aerodynamic Theory\nEarly voice researchers in the 1950's and 1960's explained vocal fold oscillation with the myoelastic-aerodynamic theory. According to these theories, Bernoulli forces (negative pressure) cause the vocal folds to be sucked together, creating a closed airspace below the glottis. Continued air pressure from the lungs builds up underneath the closed folds. Once this pressure becomes high enough, the folds are blown outward, thus opening the glottis and releasing a single 'puff' of air. \n\nThe lateral movement of the vocal folds continues until the natural elasticity of the tissue takes over, and the vocal folds move back to their original, closed position. Then, the cycle begins again. Each cycle produces a single small puff of air; the sound of the human voice is nothing more than tens or hundreds of these small puffs of air being released every second and filtered by the vocal tract. \n\nLet's further examine the myoelastic-aerodynamic theory. Myo- means muscle; the vocal folds, after all, are mostly comprised of muscle tissue. The -elastic suffix serves to remind us that the vocal fold is elastic and that we have active control over its elastic properties. Aerodynamic means that the theory deals with the motion of air and other gaseous fluids, and with the forces active on bodies in motion (such as the vocal folds) in relation to such fluids.
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Yes, it's true. Think about it.....you have a fluid that is on a rotating sphere. If you take this fluid and move it from the upper portion of the rotating sphere to the lower part, don't you think something has to change?\n\nGranted, the dynamics are extremely subtle but the effect is there. There are a lot of various forces at work due to the rotation of the earth. Performing the experiment is very difficult because any aberrations in the fluid causes error or doubt about what mechanism is actually causing the spiraling fluid flow.\n\nTake a clear bowl of water and stir it so it rotates.....then lift it up and look at it from underneath. It rotates in the opposite direction.....right? That's similar to what's going on, except the forces on the water are what causes the change in rotation. You are in essence turning the bowl upside down when you move it from one hemisphere to another.\n\nSimplified explanation, but sufficient I suppose. Hope it helps.\n\n:)
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Bionomial expansion\n\nthis has got n+1 terms\n\nthe terms are (nCk) a^kb^n-k where k varies from 0 to n\n\nfor example (a+b)^3\none term (3C0) a^0b^3 = b^3\nanother term (3C1)a^1b^2 = 3ab^2\nanother (3C2)a^2b^1 = 3a^2b\nanother (3c3)a^3b^0 = a^3\n\nadd them and get a^3+3a^2b+3ab^2+ b^3\n\n(nCk) = n!/(k!(n-k)!)\n\nThe n'th line of the pascal triangle gives you the coeffiecients . Starting from 0.