8-2 Telling Them Apart. From the following list of properties, indicate which one (s) can be used to distinguish between each of the following pairs of transport mechanisms. Transport Mechanisms (a) Simple diffusion; facilitated diffusion (b) Facilitated diffusion; active transport (c) Simple diffusion; active transport (d) Direct active transport; indirect active transport (e) Symport; antiport (f) Uniport; coupled transport (g) P-type ATPase; V-type ATPase Properties 1. Directions in which two transported solutes move 2. Direction the solute moves relative to its concentration gradient or its electrochemical potential 3. Kinetics of solute transport

Transportation across the membrane

Explanation:

(a) Simple diffusion; Faciliated diffusion-Directions in which two transported solutes move

In simple diffusion diffusion of non polar compounds across the membrane and along the concentration gradient without the involvement of protein whereas in case of facilitated diffusion membrane transport proteins that facilitate movement pf molecules across the membrane down its concentration gradient Both the diffusions does not require energy

(b) Facilitated diffusion; active transport-Direction the solute moves relative to its concentration gradient

In facilitated diffusion membrane transport proteins that facilitate movement of molecules across the membrane down its concentration gradient without the expenditure of energy Active transport drives transportation of solute against the concentration gradient across the membrane

(c) Simple diffusion; Active transport-Directions in which two transported solutes move and Direction the solute moves relative to its concentration gradient

In simple diffusion diffusion of non polar compouds across the membrane and along the concentration gradient without the involvement of protein and energy Active transport drives transportation of solute against the concentration gradient across the membrane; secondary active transporters coupled with transportation of two solute molecules

(d) Direct active transport; Indirect active transport-Direction the solute moves relative to its concentration gradient or its electrochemical potential

Direct active transport use direct energy such as ATP hydrolysis, oxidation and sunlight energy Indirect active transport use indirect energy such as chemical gradient, electrochemical gradient established by direct active transporters; one solute moves along the concentration gradient while other moves against the concentration gradient

(e) Symport; Antiport-Direction in which two transported solutes move

In symport both the solute molecules move in same direction; coupled with primary active transport (direct transport) In antiport both the solutes moves in opposite direction; coupled with secondary active transport (indirect transport)

(f) Uniport; coupled transport-Directions in which two transported solutes move

Uniport is the transport of single solute across the membrane Coupled transport is the transport of two solute molecules across the membrane; it may be symport or antiport

(g) P-type ATPase; V-type ATPase-Kinetics of solute transport

P-type ATPase always transport cations and undergoes phosphorylation V-type ATPase (here V stands for vacuole) transport protons and no phosphorylation occurs; catalytic activity is not reversible Both are types of primary active transporters