Exam 5: Membrane Transport and Cell Signaling

In receptor-mediated endocytosis, receptor molecules are initially localized on the outer surface of the plasma membrane. Where do the receptors end up following endocytosis?

Which of the following would diffuse through the lipid bilayer of a plasma membrane most slowly, if at all?

Which of the following would increase the electrochemical gradient across a membrane?

Cystic fibrosis is a genetic disease in humans in which the CFTR protein, which functions as a chloride ion channel, is missing or nonfunctional in cell membranes. The CFTR protein belongs to what category of membrane proteins?

If an animal cell suddenly lost the ability to produce GTP, what might happen to its signaling system?

Which of the following is most likely true of a protein that cotransports glucose and sodium ions into the intestinal cells of an animal?

Which of the following is one of the ways that the membranes of winter wheat are able to remain fluid when it is extremely cold?

The sodium-potassium pump is called an electrogenic pump because it

Which of the following is true of steroid receptors?

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. -At the beginning of the experiment, side A in the figure

Figure 5.2 The solutions in the two arms of this U-tube (Figure 5.2) are separated by a membrane that is permeable to water and glucose but not to sucrose. Side A is half-filled with a solution of 2 M sucrose and 1 M glucose. Side B is half-filled with 1 M sucrose and 2 M glucose. Initially, the liquid levels are equal. Refer to the figure to answer the following question(s). -After the system depicted in the figure reaches equilibrium, what changes are observed?

Water passes quickly through cell membranes because

The fluid mosaic model of the membrane proposed that membranes

At puberty, an adolescent female body changes in both structure and function of several organ systems, primarily under the influence of changing concentrations of estrogens and other steroid hormones. How can one hormone, such as estrogen, mediate so many effects?

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 or lines in the graph in the figure represent(s) bags that contain a solution that is hypertonic at 50 minutes?

Figure 5.5 -In Figure 5.5, the dots in the space between the two structures represent which of the following?

The phosphate transport system in bacteria imports phosphate into the cell even when the concentration of phosphate outside the cell is much lower than the cytoplasmic phosphate concentration. Phosphate import depends on a pH gradient across the membrane-more acidic outside the cell than inside the cell. Phosphate transport is an example of