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>
What controls what molecules pass in and out of a cell?
Sorghum and millet are the grains that thrive well in arid environments. Sorghum is a close relative of the smaller millet, with the latter measuring only a third in size to sorghum. It is important to know that sorghum is sometimes called great millet.
Every 192 -gram cup of cooked whole sorghum or millet contains 22 grams compared to wheat (16 grams), brown rice (15 grams), and maize (16 grams).
