C. The energetics of solute movement Diffusion is the spontaneous movement of material from a region of high concentration to a region of low concentration %The free-energy change during diffusion of nonelectrolytes depends on the concentration grdient The free-energy change during diffusion of electrolytes depends on the electrochemical grdient
C. The energetics of solute movement: ❖Diffusion is the spontaneous movement of material from a region of high concentration to a region of low concentration. ❖The free-energy change during diffusion of nonelectrolytes depends on the concentration grdient. ❖The free-energy change during diffusion of electrolytes depends on the electrochemical grdient
D. Transport processes within an eu karyotic cell e Camer proein Tncarbanyic acids . gy 3 Anc
D. Transport processes within an eukaryotic cell
2. Passive transport and active transport A. Comparison of two classes of transport. Table 8-2 Properties of Passive and Active Transport Diffusion(Passive Transport Properties Simple Diffusion Facilitated Diffusion Active Transport Solutes transported Examples Small nonpolar Ox Yes Large nonpolar Fatty acids Yes No Small polar No Large polar GI ucose N Ye lo N+K+ Ca No Yes Thermodynamic properties Direction relative to electrochemical gradient Down Effect on entropy Increased Increased Decreased Metabolic energy required N Intrinsic directionality N Kinetic properties Carrier-mediated Yes Yes ipump Michaelis- Menten kinetics N Yes Competitive inhibition N Yes Yes
2. Passive transport and active transport A. Comparison of two classes of transport
carrier-meditated diffusion max simple diffusion concentration of→ transported molecule Figure 11-7 Kinetics of sim ple diffusion com pared to carrier-mediated diffusion. Whereas the rate of the former is always proportional to the solute concentration, the rate of the latter reaches a maximum( Vmax when the carrier protein is saturated. The solute concentration when transport is at half its maximal value approximates the binding constant (KM) of the carrier for the solute and is analogous to the Km of an enzyme for its substrate. The graph applies to a carrier transporting a single solute; the kinetics of coupled transport of two or more solutes(see text) are more complex but show basically similar phenomena
Figure 11-7 Kinetics of simple diffusion compared to carrier-mediated diffusion. Whereas the rate of the former is always proportional to the solute concentration, the rate of the latter reaches a maximum (Vmax) when the carrier protein is saturated. The solute concentration when transport is at half its maximal value approximates the binding constant (KM) of the carrier for the solute and is analogous to the KM of an enzyme for its substrate. The graph applies to a carrier transporting a single solute; the kinetics of coupled transport of two or more solutes (see text) are more complex but show basically similar phenomena
B Two classes of membrane transport proteins Carrier proteins are responsible for both the passive and the active transport. Channel proteins are only responsible for passive transport transported molecule channel○ carrier otein protein lipid electrochemical bilayer gradient ○○ simple hannel carrie diffusion mediated mediated L diffusion diffusion PASSIVE TRANSPORT ACTIVE TRANSPORT (FACILITATED DIFFUSION
B. Two classes of membrane transport proteins ❖Carrier proteins are responsible for both the passive and the active transport. ❖Channel proteins are only responsible for passive transport