Exam 7: Membrane Structure and Function

Use the following information to answer the questions below. 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?

In order for a protein to be an integral membrane protein,it would have to be

Which correctly describes intracellular joining?

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.Using this information,which transport mechanism is most probably functioning in the intestinal cells?

Which of the following factors would tend to increase membrane fluidity?

Which of the following most accurately describes selective permeability?

Use the following information to answer the questions below. 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. -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?

Which of these are not embedded in the hydrophobic portion of the lipid bilayer at all?

Which of the following membrane activities require energy from ATP hydrolysis?

For the following questions,match the labelled component of the cell membrane in the figure with its description. -Which component is the fibre of the extracellular matrix?

In the years since the proposal of the fluid mosaic model of the cell membrane,which of the following observations has been added to the model?

Use the following information to answer the questions below. Human immunodeficiency virus (HIV)infects cells that have both CD4 and CCR5 cell surface molecules.The viral nucleic acid molecules are enclosed in a protein capsid,and the protein capsid is itself contained inside an envelope consisting of a lipid bilayer membrane and viral glycoproteins.One hypothesis for viral entry into cells is that binding of HIV membrane glycoproteins to CD4 and CCR5 initiates fusion of the HIV membrane with the plasma membrane,releasing the viral capsid into the cytoplasm.An alternative hypothesis is that HIV gains entry into the cell via receptor-mediated endocytosis,and membrane fusion occurs in the endocytotic vesicle.To test these alternative hypotheses for HIV entry,researchers labelled the lipids on the HIV membrane with a red fluorescent dye. -What would be observed by live-cell fluorescence microscopy if HIV is endocytosed first,and then fuses with the endocytotic vesicle membrane?

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

Which of the following is true of integral membrane proteins?

White blood cells engulf bacteria through what process?

Use the following information to answer the questions below. Human immunodeficiency virus (HIV)infects cells that have both CD4 and CCR5 cell surface molecules.The viral nucleic acid molecules are enclosed in a protein capsid,and the protein capsid is itself contained inside an envelope consisting of a lipid bilayer membrane and viral glycoproteins.One hypothesis for viral entry into cells is that binding of HIV membrane glycoproteins to CD4 and CCR5 initiates fusion of the HIV membrane with the plasma membrane,releasing the viral capsid into the cytoplasm.An alternative hypothesis is that HIV gains entry into the cell via receptor-mediated endocytosis,and membrane fusion occurs in the endocytotic vesicle.To test these alternative hypotheses for HIV entry,researchers labelled the lipids on the HIV membrane with a red fluorescent dye. -What would be observed by live-cell fluorescence microscopy if the red fluorescent lipid dye-labelled HIV membrane fuses with the target cell plasma membrane?

-Based on the figure above,which of these experimental treatments would increase the rate of sucrose transport into the cell?

In which of the following would there be the greatest need for osmoregulation?

Use the following information to answer the questions below. 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. -If the sodium ion concentration outside the cell increases,and the CFTR channel is open,in what direction will chloride ions and water move across the cell membrane?

The fluid mosaic model of the membrane proposes that membranes