Here something that might help
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Most scientists believe that for half of </span>Earth's<span> 4.6-billion-year history, the</span>atmosphere<span> contained almost no </span>oxygen<span>. Cyanobacteria or blue-green algae became the first microbes to produce </span>oxygen<span> by photosynthesis, perhaps as long ago as 3.5 billion years ago and certainly by 2.7 billion years ago.</span>
Loop Diuretics
These are diuretics that exerts effect on the loop of Henle. They are primarily used in heart failure, hypertension and edema. In contrast with Thiazides, loop diuretics are more effective in patients with abnormal kidney function. Loop diuretics inhibit the magnesium and calcium reabsorption in the thick ascending limb of Henle. Loop diuretics is highly protein bound. It has volume of distribution that is limited. This causes the diuretics to be secreted in the convuluted tubules to exert its function.
Answer:
The two main reasons are nonpolar core of the bilayer and the active transport.
Explanation:
The membrane is structured to have two outer layers that are polar and an inner layer that is nonpolar.
If a membrane protein is exposed to the solvent, i<em>t will also have a polar side. It would be very difficult for the polar face of the membrane to move through the nonpolar core of the bilayer.</em> Therefore, this model is not feasible.
One major form of transport, active transport, moves solutes up the concentration gradient. <em>The binding of a solute and then release on another side of the membrane would only work for facilitated diffusion because it would cause a net movement of solutes down the concentration gradient.</em> It is unclear how energy could be expended to drive this process in the transverse carrier model.<em> Therefore, the transverse carrier model does not explain active transport.</em>
