Biology Reference
In-Depth Information
FIGURE 14.5
(a) Simple passive diffusion (Top, Left) and (b) Facilitated diffusion (Top, Right). Passive diffusion
results in a final equilibrium distribution of a solute across the membrane. For a non-charged solute, the final
distribution of the solute would find equal amounts of S on both sides of the membrane. Facilitated diffusion
employs a specific transporter and exhibits Michaelis-Menten saturation kinetics. Active transport (Bottom) utilizes
energy, often in the form of ATP, to drive solute uptake against its gradient resulting in a net accumulation of the
solute.
membrane outer surface site causing a conformational change associated with transport,
releasing glucose to the inner side of the membrane where it enters into the internal aqueous
solution (
Figure 14.6
).
Potassium Channels
In virtually all organisms there exists a wide variety of ion channels, the most widely
distributed being potassium channels
[11]
. There are four basic classes of potassium
