Page 111 - The Miracle in the Cell Membrane

THE VARIOUS METHODS OF ENTRY IN THE CELL

MEMBRANE ARE PROOF OF CONSCIOUS CREATION
High Low concentration
concentration Diffusion from the fat layer:

Molecules such as O2 and CO , which are soluble
2
in fat, pass freely through the cell membrane.
Diffusion among the channels:
Some polarized and electrically charged molecules
pass through protein channels forming a bridge on
the cell membrane. Water is a typical example.

Facilitated Diffusion:
Some molecules attach to a protein. The molecule
causes a change in the shape of the protein. In
this way, the molecule is able to pass through the
cell membrane. Glucose enters the cell in this
way.

The above diagram shows the simple diffusion and facilitated diffusion meth-
ods of passing materials through the cell membrane. If the substance to enter
the cell is dissolved in fat, then it enters the cell through gaps in the double-lay-
ered lipid layer. If not fat-soluble, then it enters through the water-filled chan-
nels of certain transport proteins. As you see, the structure of the cell mem-
brane is ideally suited to letting necessary substances enter the cell.

chan nel that is closed on the inside opens up, and the
mol e cule enters from there. When it reach es a site close to
the inside of the cell, the pro tein splits away from the
mol e cule with ther mal motion,—stem ming from heat—
because the mol e cule is bound to it only weak ly, and thus
the mol e cule enters the cell.
Under this mech a nism, the speed at which the mol e -
cu les are trans port ed is as great as the alter a tion in the
shape of the trans port pro tein mol e cule. By this meth od,
the sub stance being trans port ed can pass in both direc -

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