the Na+–amino acid symporters in the apical domain of the plasma membrane.

continue to pump ions without hydrolyzing ATP.

is mediated by microtubule transport directed to the basolateral versus the apical plasma membranes.

Questions 44-48 Nuclear-cytoplasmic transport

is catalyzed by import and export receptor-FG repeat interactions through the nuclear pore complex.

(A) Diagram the structure of the nucleus. Indicate the aspects important for nuclear-cytoplasmic compartmentalization and transport. (2 pts.) (B) Diagram the general structure of the nuclear pore complex. (2 pts.) (C) Diagram the functional role of the phenylalanine-glycine repeats (FG repeats) in facilitating the passage of nuclear import/export receptor passage through the nuclear pore complex.  Do the FG repeats function to change the

no energy is lost as heat.

have been shown to cause cancer.

completely stops in the absence of O2.

(A) Diagram the process of glucose transport from the lumen of the small intestine to the blood through an epithelial cell. (1 pt.) (B) Name the three transmembrane transporters involved, what they transport, and what energy sources they use.   Indicate where passive transport and primary and secondary active transport are involved and the relative (for example higher or lower) concentrations of Na+, K+, and glucose in the lumen, blood and cytoplasm and where uniport, antiport and symport are involved. (3 pts.) (C) Diagram and describe the mechanism of primary active transport by the Na+/K+ ATPase (Na+ pump). (5 pts.) (D) Oubain and digitoxin are drugs that inhibit the K+ dependent phosphatase activity of the Na+/K+ ATPase pump. How do these two drugs cause the heart muscle cells to contract more strongly in patients with heart disease?  (3 pts.) (E) Diagram or describe the mechanism of secondary active transport (symport) by Na+/glucose transporters using the electrochemical potential energy of a Na+ gradient to accomplish the active transport of glucose. How is the negative free energy change (-DG) of Na+ passage into the cell tied (physically) to transport of glucose against a concentration gradient? (3 pts.)