Problem 1
Name some of the features common to all membranes.
Problem 2
What conditions are required for a small molecule to spontaneously pass through a membrane?
Problem 3
Match each term with its description. (a) Integral membrane protalin _____________ (b) Peripheral membrane protein_________________ (c) Channel__________________ (d) Passive transport___________________ (e) Active transport_______________________ (f) \(\mathrm{Na}^{+}-\mathrm{K}^{+}\) ATPase_______________ (g) Secondary transporter_________________ (h) Antiporter___________________ (i) Symporter______________________ (j) Ion channel______________________ 1\. Facilitated diffusion 2\. Uses the energy of one gradient to create another 3\. Interacts tightly with the membrane interior 4\. Molecules moving in opposite directions 5\. Interacts with the border of a membrane 6\. Allows rapid movement of molecules down a gradient across a membrane 7\. Movement against a concentration gradient 8\. Molecules moving in the same direction 9\. Can be voltage-gated or ligand-gated 10\. Inhibited by digitalis
Problem 4
Arrange the following substances in order of increasing permeability through a lipid bilayer: (a) glucose; (b) glycerol; (c) \(\mathrm{Cl}^{-} ;\) (d) indole; (e) tryptophan.
Problem 5
Differentiate between simple diffusion and facilitated diffusion.
Problem 6
Differentiate between passive transport and active transport.
Problem 7
Proper membrane fluidity is vital to membrane-protein function. Suggest how a loss of fluidity and how too much fluidity might affect membrane-protein function.
Problem 8
Outline the relation between the \(\mathrm{Na}^{+}-\mathrm{K}^{+}\) ATPase and the strength of a heart contraction. Identify the relevant primary and secondary active-transport components. How do cardiotonic steroids affect the strength of a heartbeat?
Problem 9
Somali hunters use arrows that have been dipped in high concentrations of the cardiac glycoside ouabain to kill game. Indeed, there are reports that animals the size of a hippopotamus can be killed by ouabain-treated arrows. Suggest a biochemical basis for the lethal action of ouabain.
Problem 11
What are two fundamental properties of all ion channels?
