Exam 5: Membrane Transport and Cell Signaling

Glucose diffuses slowly through artificial phospholipid bilayers. The cells lining the small intestine, however, rapidly move large quantities of glucose from the glucose-rich food into their glucose-poor cytoplasm. Based on this information, which transport mechanism is most likely responsible for glucose transport in the intestinal cells?

Which of the following is true of integral membrane proteins?

Which of the following statements about diffusion is correct?

A major group of G protein-coupled receptors contains seven transmembrane α helices. The amino end of the protein lies at the exterior of the plasma membrane. Loops of amino acids connect the helices either at the exterior face or on the cytosol face of the membrane. The loop on the cytosol side between helices 5 and 6 is usually substantially longer than the others. The coupled G protein most likely interacts with this receptor

Figure 5.3 The solutions in the arms of a U-tube (Figure 5.3) are separated at the bottom of the tube by a selectively permeable membrane. The membrane is permeable to sodium chloride but not to glucose. Side A is filled with a solution of 0.4 M glucose and 0.5 M sodium chloride (NaCl), and side B is filled with a solution containing 0.8 M glucose and 0.4 M sodium chloride. Initially, the volume in both arms is the same. Refer to the figure to answer the following questions. -If you examine side A in the figure after three days, the concentrations of glucose and NaCl should be

In which of the following ways could signal transduction most probably be explored in research to treat cancer?

Why are lipids and proteins free to move laterally in membranes?

How do unsaturated fatty acids help keep any membrane more fluid at lower temperatures?

Lipid-soluble signaling molecules, such as aldosterone, cross the membranes of all cells but affect only target cells because

The difference between pinocytosis and receptor-mediated endocytosis is that

Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because

Which of the following is true for the evolution of cell membranes?

Which of the following is the first event that occurs following the binding of a ligand by a membrane receptor protein?

Figure 5.4 Five dialysis bags, constructed from a semipermeable membrane that is impermeable to sucrose, were filled with various concentrations of sucrose and then placed in separate beakers containing an initial concentration of 0.6 M sucrose solution. At 10-minute intervals, the bags were massed (weighed) and the percent change in mass of each bag was graphed. Refer to Figure 5.4 to answer the following question(s). -Which line in the graph represents the bag that contained a solution isotonic to the 0.6 M solution at the beginning of the experiment?

The movement of the hydrophobic gas nitrous oxide (N2O) (laughing gas) into a cell is an example of

According to the fluid mosaic model of cell membranes, which of the following is a true statement about membrane phospholipids?

Figure 5.1 For the following questions, match the labeled component of the cell membrane in Figure 5.1 with its description. -Which component in the figure helps membranes resist changes in fluidity at high and low temperatures?

Figure 5.1 For the following questions, match the labeled component of the cell membrane in Figure 5.1 with its description. -Which component in the figure is a glycolipid?

Familial hypercholesterolemia is characterized by extremely high levels of cholesterol in the blood, which results from

The primary function of kinases in signal transduction is to